"No text has been approved for an initial memorandum of understanding with the United States," said Fars, quoting what it said was an informed source close to Iran's negotiating team.

US President Donald Trump had earlier said he had called off planned strikes on Iran and flagged the signing of a possible deal with Tehran.

"Based on the fact that discussions with the Islamic Republic of Iran have been brought to the highest level of Iranian leadership and approved, I have... cancelled the scheduled strikes and bombings against Iran this evening," Trump posted on his Truth Social network.

There has been no official comment from Iran on a possible deal with the United States.

Iran's Tasnim news agency dismissed Trump's announcement, saying the US president had made similar declarations in the past without any outcome.

"Until Iran announces the matter of a potential understanding, any news from Trump on this subject should be regarded as his previous messages," it said.

Tehran and Washington have been swapping proposals to end the war, which broke out on February 28 and engulfed the Middle East.

In recent days, the two sides have increasingly engaged in exchanges of fire despite a fragile ceasefire has been in place since April 8.