Foreign Minister Jean-Yves Le Drian told reporters ahead of the UN General Assembly that scrapping the 2015 agreement would launch an arms race with "neighboring countries that would feel encouraged to head into the same direction."
US President Donald Trump has threatened to scrap the nuclear agreement, describing it as the "worst deal ever negotiated."
"France will try to persuade President Trump of the importance of this choice, even if it can be completed by work after 2025," he said ahead of a meeting between Trump and French President Emmanuel Macron later in the day.
"It's essential to maintain (the agreement) to prevent a spiral of proliferation that would encourage hardliners in Iran to pursue nuclear weapons," Le Drian said.
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France and the United States are among the six powers that negotiated the landmark agreement with Iran. Britain, China, Germany and Russia are also part of the deal.
Under the nuclear deal, Iran surrendered much of its enriched uranium, dismantled a reactor and submitted nuclear sites to UN inspection, while Washington and Europe lifted some sanctions.
Iranian President Hassan Rouhani is scheduled to speak on Wednesday.
Trump is due to decide before October 15 whether Iran has breached the 2015 nuclear agreement, and critics fear he may abandon an accord they think prevents Tehran from building a nuclear bomb.
US Secretary of State Rex Tillerson will join his Iranian counterpart Mohammad Javad Zarif on Wednesday for a meeting of the so-called E3+3 on the nuclear deal, chaired by the European Union.
"Military action is not required," said the foreign minister.
"To bring North Korea to the negotiating table, the only possible way is to apply very strong pressure," he added.
The UN Security Council last week imposed a new raft on sanctions on North Korea after it carried out its sixth and most powerful nuclear test.