Other world leaders gathered in Japan continued to express concern about Iran, even as Trump appeared relaxed
Diplomats said Iran is on course to breach a threshold in its nuclear agreement within days but US President Donald Trump, who has ratcheted up pressure on the Middle Eastern country, said there was "absolutely no time pressure" on the issue.
The prospect that Tehran could soon violate its nuclear commitments, a week after Trump called off air strikes on Iran at the last minute, has created additional diplomatic urgency to find a way out of the crisis.
Iran had set Thursday as a deadline beyond which it would exceed the threshold for stockpiles of enriched uranium allowed under its 2015 nuclear deal with major powers, which Tehran is still following even though Washington abandoned it last year.
The diplomats, citing UN inspectors' data, said the Islamic Republic was on course to exceed the limits soon by accumulating more enriched uranium than permitted but it had not done so by Thursday.
However, Trump said of Iran on Friday: "We have a lot of time. There's no rush."
"They can take their time. There's absolutely no time pressure. I think in the end, hopefully, it's going to work out. If it does, great - and if it doesn't, you’ll be hearing about it," he said as he greeted Indian Prime Minister Narendra Modi on the sidelines of a G20 summit in Osaka.
Other world leaders gathered in Japan continued to express concern about Iran, even as Trump appeared relaxed.
Chinese President Xi Jinping said the Gulf region was "standing at a crossroads of war and peace," calling for calm and restraint and talks to resolve the issue.
"China always stands on the side of peace and opposes war," state news agency Xinhua paraphrased Xi as saying in Osaka. "All parties must remain calm and exercise restraint, strengthen dialogue and consultations, and jointly safeguard regional peace and stability."
European Council President Donald Tusk, also at the G20, expressed concern about Iran potentially breaching the pact, saying the European Union would continue to monitor Tehran's compliance.
"We strongly urge Iran to continue the full implementation of all its commitments under the nuclear deal, and we take very seriously the possibility of any breach of its commitment," he told a news conference.
"Maintaining the nuclear deal is in the regional and international security interest," Tusk said. "The EU is committed to the deal as long as Iran continues to uphold it."
One diplomat in Vienna, headquarters of the UN nuclear agency the International Atomic Energy Agency (IAEA), said on Thursday: "They haven't reached the limit ... It's more likely to be at the weekend if they do it."
The US envoy on Iran, Brian Hook, met European officials in Paris on Thursday to discuss what he described as Iran's "nuclear blackmail."
France, one of the European countries caught in the middle, said it would ask Trump to suspend some sanctions on Iran to make room for negotiations to defuse the escalating confrontation between Washington and Tehran.
"I want to convince Trump that it is in his interest to reopen a negotiation process (and) go back on certain sanctions to give negotiations a chance," French President Emmanuel Macron said in Japan on Thursday.
The United States withdrew last year from the pact, under which Iran accepted curbs on its nuclear program in return for relief from economic sanctions. Iran has said it wants to abide by the agreement but cannot do so indefinitely because US sanctions mean it is receiving none of its benefits.
The escalating crisis has put the United States in the position of demanding its European allies enforce Iranian compliance with an accord Washington itself rejects.
"Our sanctions do not give Iran the right to accelerate its nuclear program," Hook said in an interview before meeting European officials. "It can never get near a nuclear bomb. We are looking very closely at that so it doesn't get below the one-year nuclear breakout time."
The confrontation, brewing for a year after Trump quit the pact, accelerated last month when the United States sharply tightened its sanctions to force countries to eliminate purchases of Iranian oil, Tehran's main source of income.
US-Iranian military tensions have risen over the past two months. Washington accused Iran of carrying out attacks on six tankers in May and June, which Tehran denies.
Iran shot down a US drone last week it said was in its airspace. The United States said it was in international skies.
Trump said later he hoped to avoid war but that, if one took place, it would be short and not involve boots on the ground. Iranian Foreign Minister Mohammad Javad Zarif said on Twitter in response on Thursday a "short war with Iran is an illusion," and the threat to obliterate Iran amounted to a threat of genocide.
Acting US Defense Secretary Mark Esper, seeking support from NATO allies in Brussels, said: "We do not seek armed conflict with Iran but we are ready to defend US forces and interests in the region."
The Trump administration says its ultimate goal is to force Iran back to the table for negotiations. It argues that the 2015 deal, negotiated under Trump's predecessor, Barack Obama, was too weak because it was not permanent and did not cover non-nuclear issues, such as Iran's missile program and regional behavior.