The New York Times | Mark Landler, Maggie Haberman and Eric Schmitt: President Trump has sought to put the brakes on a brewing confrontation with Iran in recent days, telling the acting defense secretary, Patrick Shanahan, that he does not want to go to war with Iran, administration officials said, while his senior diplomats began searching for ways to defuse the tensions.

Mr. Trump�s statement, during a Wednesday morning meeting in the Situation Room, sent a message to his hawkish aides that he does not want the intensifying American pressure campaign against the Iranians to explode into open conflict.

For now, an administration that had appeared to be girding for conflict seems more determined to find a diplomatic off-ramp.

Secretary of State Mike Pompeo called the leader of Oman, Sultan Qaboos bin Said, on Wednesday to confer about the threat posed by Iran, according to a statement. Long an intermediary between the West and Iran, Oman was a site of a secret channel in 2013 when the Obama administration was negotiating a nuclear agreement with Iran.

Mr. Pompeo also asked European officials for help in persuading Iran to �de-escalate� tensions, which rose after American intelligence indicated that Iran had placed missiles on small boats in the Persian Gulf. The intelligence, which was based on photographs that have not been released but were described to The New York Times, prompted fears that Tehran may strike at United States troops and assets or those of its allies.

Asked on Thursday whether the United States was going to war with Iran, Mr. Trump replied, �I hope not.�

The developments cast into sharp relief a president who is instinctively wary of military adventures and a cadre of advisers � led by the national security adviser, John R. Bolton � who have taken an uncompromising line toward Iran. The internal tensions have prompted fears that the Trump administration is spoiling for a fight, even if the commander in chief may not be.

Those divisions are playing out against a fierce internal debate among administration officials about the gravity of the Iranian threat. While officials and British allies say the intelligence about the threat is valid, lawmakers and some inside the administration accuse Mr. Trump�s aides of exaggerating the danger and exploiting the intelligence to justify a military clash with Tehran.

The administration�s internal debate over Iran was described by five senior officials who demanded anonymity to discuss sensitive internal deliberations.

Iran dismissed any suggestion of a dialogue with Mr. Trump. �The escalation by the United States is unacceptable,� the Iranian foreign minister, Mohammad Javad Zarif, said Thursday.

Indeed, there was a new potential flash point in Iran�s standoff with the United States, stemming from its vow last week to step away from some of the limitations imposed by the nuclear deal, a year after Mr. Trump pulled the United States out of the agreement that was negotiated between Tehran and world powers in 2015.

State Department officials, speaking to reporters, set a red line that they warned Iran would cross at its peril: It could not ramp up its nuclear fuel production to the point where it could produce a nuclear weapon in less than one year.

The officials did not specify what kind of reaction � military or otherwise � would come if Iran built up enough of a stockpile of uranium and took other steps to cross that threshold. But they acknowledged that the steps announced by Iran�s president, Hassan Rouhani, could eventually give Tehran that ability.

No new information was presented to Mr. Trump at the Situation Room meeting that argued for further engagement with Iran, according to a person who attended.

Mr. Shanahan and Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, presented the president with a range of military options and checked off the troop levels, costs and risks of each, one of the officials said.

But Mr. Trump was firm in saying he did not want a military clash with the Iranians, several officials said.

The president has sought to tamp down reports of divisions among Mr. Bolton, Mr. Pompeo and the Pentagon. Military officials have warned against escalating the confrontation, even as Mr. Bolton ordered the Pentagon to present options to send as many as 120,000 troops to the Middle East to respond to Iranian provocations.

�There is no infighting whatsoever,� Mr. Trump said Wednesday on Twitter. �Different opinions are expressed and I make a decisive and final decision - it is a very simple process. All sides, views, and policies are covered.�

Mr. Trump added that he was confident that Iran �will want to talk soon,� though one senior official said the White House was highly unlikely to pursue a secret diplomatic channel for talking to Iran, as the Obama administration had done.

Mr. Pompeo has outlined 12 steps that Iran must take to satisfy the United States � including halting all ballistic missiles tests and cutting off support for militant groups in Syria and Yemen � which critics in the Pentagon view as unrealistic and could back Iranian leaders into a corner. He recently described American policy as being calculated to produce domestic political unrest in Iran.

But for all of his harsh words toward Tehran, several officials said Mr. Pompeo was rankled by being lumped in with Mr. Bolton as bent on war. A former Republican lawmaker, Mr. Pompeo is an astute reader of Mr. Trump�s preferences and will plunge into diplomacy, if necessary, as he has with North Korea.

Mr. Bolton, as a private citizen, long called for regime change in Tehran. He has resisted compromises that would open the door to negotiations, has stocked the National Security Council with Iran hard-liners and has masterminded recent policy changes to tighten the economic and political vise on the clerical government in Tehran.

Three officials said Mr. Trump is less frustrated with Mr. Bolton over his handling of Iran � he favors the tougher measures as a warning to Tehran � than over the evolving narrative that his national security adviser is leading the administration�s policy in the Middle East.

The president, they said, is well versed and comfortable with the administration�s recent steps, which have included imposing increasingly onerous sanctions on Iran and designating an arm of the Iranian military, the Islamic Revolutionary Guards Corps, a foreign terrorist organization.

Some officials have argued that Iran�s actions did not warrant a significant American response, like potentially deploying thousands of troops to the Middle East, or the partial evacuation of the United States Embassy in Baghdad.

�It�s a situation where this president has surrounded himself with people, Pompeo and Bolton in particular, who believe that getting tough on a military basis with Iran is in our best interest,� said Senator Richard J. Durbin of Illinois, the No. 2 Democrat, as he emerged from an intelligence briefing on Thursday. �I do not.�

Mr. Bolton, several of the officials said, has quietly voiced frustration with the president, viewing him as unwilling to push for changes in a region that he has long seen as a quagmire. He has kept an unusually tight grip on the policymaking process for a national security adviser.

Mr. Bolton�s independence has rankled the acting chief of staff, Mick Mulvaney, and has even prompted rumors that his job might be in jeopardy � something the White House denies.

But Mr. Trump has poked fun at Mr. Bolton�s reputation for hawkishness, joking in meetings with him. �If it was up to John, we�d be in four wars now,� one of the senior officials recalled Mr. Trump as saying.

Mr. Trump is also impatient with another of Mr. Bolton�s campaigns: the effort to oust President Nicol�s Maduro in Venezuela. After the opposition�s failed attempt to peel away key Maduro allies and turn the Venezuelan military against him, Mr. Maduro appears harder to dislodge than ever.

In recent days, officials said, Mr. Trump has begun consulting outsiders, including Jack Keane, the former Army vice chief of staff and architect of the Iraq war troop surge who now appears regularly on Fox News.

Mr. Keane declined to discuss any conversations he had with Mr. Trump, but said, �I�m confident that we�re not heading to a war with Iran, and whatever measures we will use, if in fact Iran does something provocative, will be measured and deliberate in not tolerating provocation.�

Other former government officials, however, criticized the Trump administration�s policy as hobbled by internal disarray.

Derek Chollet, an assistant secretary of defense for international security affairs under President Barack Obama, said the Trump administration was �riddled by a fundamental contradiction � a president who wants to withdraw from the Middle East and an administration with a maximalist policy of regime change.�

Diplomats who were involved in negotiations with Iran during the Obama administration said intermediaries like Oman could theoretically ease the tensions. But they said the White House�s unyielding position � epitomized by Mr. Pompeo�s 12 demands � would make fruitful negotiations impossible.

�Reinserting diplomacy into the strategy is not just about signaling that you want to talk and finding a channel, but about actually being ready to talk realistically,� said William J. Burns, a former deputy secretary of state who led the secret talks with Iran and recently published �The Back Channel,� an account of the diplomacy.

Reporting was contributed by David E. Sanger, Helene Cooper, Edward Wong and Annie Karni.