French President Emmanuel Macron said in a statement on Tuesday that he recalled "his attachment to the full respect of the 2015 nuclear accord and asks Iran to reverse without delay this excess, as well as to avoid all extra measures that would put into question its nuclear commitments."
The statement added that Macron would take steps in the coming days to ensure Iran met its obligations and continued to benefit from the economic advantages of the deal.
Iran announced on Monday it had amassed more low-enriched uranium than permitted under its 2015 nuclear deal with world powers, drawing a warning from US President Donald Trump that Tehran was "playing with fire."
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Tehran's announcement marked its first major step beyond the terms of the pact since the United States pulled out of it more than a year ago. However, Iranian Foreign Minister Mohammad Javad Zarif said the move was not a violation of the accord, arguing that Iran was exercising its right to respond to the US walkout.
The step, however, could have far-reaching consequences for diplomacy at a time when European countries are trying to pull the United States and Iran back from confrontation. It comes less than two weeks after Trump said he ordered air strikes on Iran, only to cancel them minutes before impact.
Iran's semi-official Fars news agency reported that the country's enriched uranium stockpile has now passed the 300-kg (661 lb) limit allowed under the deal.
The UN nuclear watchdog, the International Atomic Energy Agency (IAEA), which monitors Iran's nuclear programme under the deal, confirmed in Vienna that Tehran had breached the limit.
Trump, asked if he had a message for Iran, said, "No message to Iran. They know what they're doing. They know what they're playing with, and I think they're playing with fire. So, no message to Iran whatsoever."
The White House said earlier it would continue to apply "maximum pressure" on Iran "until its leaders alter their course of action." It also said Iran should be held to a standard barring all uranium enrichment.