"Consultations through mediators are very intensive. We have presented our conditions and proposals and everything depends on the political rationality of Washington," Iranian Foreign Minister Abbas Araqchi said in comments carried by state media outlet IRNA.
"If the US accepts our conditions, the Strait of Hormuz will be reopened and negotiations will be resumed," he said.
Amid fears the conflict could reignite after Tuesday's midterm elections in the United States, China and Russia both spoke out on Monday against the possibility of renewed military action in a war that has hit the global economy.
While oil prices fell nearly four per cent on Monday on hopes that the latest round of mediation could lead to a diplomatic solution to the crisis, Iranian sources said they believed a new US attack was still more likely than a deal.
Iran's foreign ministry spokesman Esmaeil Baghaei said the plan Iran had submitted in September to end the war remained the focus of discussions but he confirmed comments attributed to Araqchi on Saturday that the proposal could be shortened.
"The basis of dialogue and talks between Iran and the US via mediators is still Iran's seven-step proposal, which is now condensed, making it possible to implement it within two days," he said.
US President Donald Trump rejected the seven-step proposal in September.
The plan would call for the US to end its blockade on Iranian ports, Iran to reopen the Strait of Hormuz waterway, a US waiver on Iranian oil sales, the cancellation of new sanctions on Iran and then talks on other issues.
Baghaei reiterated that condensing the plan would not change Iran's underlying stance that a return to talks on the country's nuclear program could only happen after it verified that all its conditions were met.
Asked whether the possibility of transferring Iran's highly enriched uranium stockpile to another country was raised in the talks, and whether Iran might agree to that, he said no.
An official briefed on the talks said Iran's negotiators had left on Sunday but not because of any problems in the talks, and added that a draft proposal was being circulated without elaborating.
The war, which the US and Israel launched suddenly on February 28, has led to Iran's closure of the key Strait of Hormuz waterway, the US blockade on Iranian ports and repeated bouts of Iranian drone and missile fire on Gulf states.
Trump has repeatedly said there would be no new attack on Iran before Tuesday's midterm elections.
Iran has said it will respond to any resumed attack aggressively with plans to strike targets both within and outside the Middle East.
Chinese Foreign Minister Wang Yi said on Monday that all parties to the conflict should focus on political solutions rather than resorting to arms again after a meeting with senior Iranian security official Ali Bagheri Kani in Beijing.
The Russian foreign ministry said reports of new military action against Iran were a cause for extreme concern and called for increased diplomatic efforts.
