Iran has urged Washington to act fast to return to the 2015 nuclear accord, pointing out legislation passed by parliament forces it to harden its nuclear stance if US sanctions are not eased by 21 February.
Foreign Minister Mohammad Javad Zarif also on Saturday referred to elections in Iran in June. If a hardline president is elected, this could further jeopardise the deal.
"Time is running out for the Americans, both because of the parliament bill and the election atmosphere that will follow the Iranian New Year," he told Hamshahri newspaper.
Iran's new year begins on 21 March.
The parliament, dominated by hardliners, set a two-month deadline in December for an easing of sanctions.
US President Joe Biden's administration is exploring ways to restore the nuclear deal Iran signed with world powers but was abandoned in 2018 by former President Donald Trump, who restored sanctions.
Iran retaliated by breaching the terms of the accord in a step-by-step response. Last month, it resumed enriching uranium to 20 per cent - a level achieved before the accord.
Mr Biden has said if Tehran returned to strict compliance with the pact, Washington would follow suit and use that as a springboard to broader agreement that might restrict Iran's missile development and regional activities.
Tehran has said Washington must ease sanctions before it resumes compliance and ruled out negotiations on wider security issues such as Iran's missile program.
US Secretary of State Antony Blinken discussed Iran on Friday in a virtual meeting with his British, French and German counterparts as the group weighed how to revive the deal.
"The more America procrastinates, the more it will lose ... it will appear that Mr Biden's administration doesn't want to rid itself of Trump's failed legacy," Mr Zarif said in the interview.
"We don't need to return to the negotiating table. It's America that has to find the ticket to come to the table," he added.
On Monday, Mr Zarif hinted at a way to resolve the impasse over which side moves first, by saying the steps could be synchronised.
In the latest steps by Iran to develop its missile program, the Iranian military on Saturday opened a plant to produce hybrid solid fuel for missiles and a factory to build shoulder-fired rockets.
Separately, Iran's Foreign Ministry said on Saturday a new US stand on the Yemen war could be helpful, after Mr Biden said this week Washington was ending its support for a Saudi Arabia-led military campaign in Yemen.
"Stopping support ... for the Saudi coalition, if not a political manoeuvre, could be a step towards correcting past mistakes," state media quoted ministry spokesman Saeed Khatibzadeh as saying.
But he added that this alone would not solve Yemen's problem.
Mr Biden said on Thursday the more than six-year war, widely seen as a proxy conflict between Saudi Arabia and Iran, "has to end".
