Reuters - Iran can only lose by negotiating with the United States and must be careful to limit any dealings with some �untrustworthy� European states, the Islamic Republic�s top leader said on Wednesday.

Tensions ramped up between the United States and Iran after President Donald Trump withdrew from a multilateral nuclear deal last year and reimposed sanctions.

The U.S. sanctions are putting unprecedented pressure on Iran, Supreme Leader Ayatollah Ali Khamenei said last month.

Tehran has now turned to the remaining signatories, particularly the European powers - France, Germany and Britain - to salvage the deal.

�With regard to America, no problem can be resolved and negotiations with it have nothing but economic and spiritual loss,��Ayatollah Khamenei wrote on his official website.

�Today, the Iranian people see some European countries as cunning and untrustworthy along with the criminal America. The government of the Islamic Republic must carefully preserve its boundaries with them.�

�Iran must not retreat a single step from national and revolutionary values.�

Ayatollah Khamenei pointed to sanctions as a big external challenge for the country and added, in an apparent jab at pragmatist President Hassan Rouhani, �weakness in managment� was one of the biggest internal challenges.

France, Germany and Britain opened a new channel for non-dollar trade with Iran last month to avert U.S. sanctions but top Iranian officials have said that Europe has not done enough to keep the deal intact.

Reporting by Babak Dehghanpisheh; additional reporting by Bozorgmehr Sharefedin in London, Editing by Alison Williams, William Maclean