The United States, Germany, France and Britain urged Iran on Saturday to resume compliance with a 2015 nuclear deal in order to "avoid a dangerous escalation".
Leaders of the four countries, who are hoping to persuade Tehran to stop enriching uranium to near-weapons-grade levels, said they wanted a negotiated solution.
"This will only be possible if Iran changes course," US President Joe Biden, German Chancellor Angela Merkel, French President Emmanuel Macron and British Prime Minister Boris Johnson said in a joint statement.
"We call upon President (Ebrahim) Raisi to seize this opportunity and return to a good faith effort to conclude our negotiations as a matter of urgency. That is the only sure way to avoid a dangerous escalation, which is not in any country's interest," they said after meeting on the sidelines of a summit of the Group of 20 richest nations.
The four leaders met to discuss Iran while in Rome to attend the G20 summit.
The 2015 nuclear deal unravelled after then-US President Donald Trump withdrew from it in 2018, prompting Iran to breach various limits on uranium enrichment.
Merkel said she was deeply concerned by Iran's uranium enrichment.
"We are counting on a return of Iran to the negotiating table. But the clock is ticking. Uranium enrichment is occurring in Iran and this deeply concerns us," she said on the sidelines of the G20 meeting.
An EU diplomat said the hint about lifting sanctions as an incentive for Iran to resume talks was "very clear", adding that Western powers should however be ready if Iran continued its policies but had yet to decide at what point they should react if it did.
Talks between Iran and world powers aimed at salvaging the deal, which started in April, are slated to resume at the end of November, the Islamic Republic's top nuclear negotiator said on Wednesday.
Asked as he went into Saturday's meeting when he wanted the Iran talks to resume, Biden said only: "They're scheduled to resume".
A senior US administration official told reporters the meeting had been suggested by Merkel with the aim of giving leaders an opportunity to review the issues ahead of the resumption of the talks.
"Our conviction is that if the United States and Europe are united and the United States and the entire P5+1 pull together, the diplomatic solution is the best solution to preventing Iran from getting a nuclear weapon," the official said, referring to the UN Security Council's five permanent members, plus Germany.
"And so they talked about (...) how we can effectively shape the environment to give diplomacy the best chance of succeeding in the fastest possible timeframe to put a lid back on Iran's nuclear program," the official added.
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