IRNA � US officials have failed in their efforts to put pressure on the International Atomic Energy Agency (IAEA) to not confirming Iran's commitment to its obligations under the nuclear agreement, a senior international relation expert said.

Speaking to the Islamic Republic News Agency (IRNA) on Saturday, Ali Khorram said that the US strategy is clear.

'Even under (former US president) Barack Obama, the neocons in the US Congress were pursuing a plan to kill the nuclear agreement signed between Iran and world major powers in 2015,' Khorram said.

Their first plan, launched against Iran by President Donald Trump administration, was aimed at harassing Iran by imposing new sanctions to make the country withdraw from the agreement, he added, referring to the international nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA).

They put Iran under sanction, despite a report by the IAEA that Tehran has been committed to all its obligations, Khorram said.

US Secretary of State, Rex Tillerson, who personally believes in the landmark deal and engaging with Iran, submitted the report to President Trump and he had to confirm the report despite his anger.

'That's why Trump put in charge the White House to address Iran's nuclear deal instead of allowing the State Department to deal with the issue,' he said.

This way, he (Trump) could prevent verification of Iran's performance in regard with the nuclear deal, the international relation expert said.

Khorram went on to say that Washington's Plan B, however, focused on pressing the IAEA by urging the United Nation nuclear watchdog to ask for having access to Iran's military sites, in order that the agency could not confirm Iran's commitment easily.

He said that the visit to Vienna by US Ambassador to the UN, Nikki Haley, was aimed at achieving the same goal, Khorram added.

'The US officials are trying by adopting various tactics to find fault with Iran,' the former Iran's representative in UN headquarter in Geneva said, adding that Iranian Foreign Minister Mohammad Javad Zarif only pursues the issue through diplomacy and negotiation.

'On one hand, Zarif contacts the EU and other signatories of the JCPOA and asks them for arbitration, and on the other, he negotiates with the IAEA to convince them that requesting access to Iran military facilities is an excessive demand,' Khorram said.

'Zarif is also trying to convince the IAEA not to prepare any two-sided report out of fear of the US,' he said.

Haley has visited the Agency in recent days to press the UN on Iran's nuclear activity verification. She repeated her demands on Friday at the IAEA to seek access to Iranian military sites for verifications.