The French President Emmanuel Macron has proposed a “new” Iran nuclear deal to build on the one currently in place, a diplomatic gamble that he hopes will convince Donald Trump not to scrap the landmark accord.

“I would like us to have a new deal with the four pillars that already exist in the current [agreement],” Mr Macron said during a joint press conference in the White House. “This is the only way to bring about stability.”

The French leader made the comments after a morning of pomp and circumstance in Washington to celebrate the first state visit during Mr Trump’s presidency,

The US leader welcomed his counterpart in a grand ceremony that saw nearly 500 US service members from all of America’s branches of military participate in a “Review of the Troops”.

"If Iran threatens us in any way, they will pay a price like few countries have ever paid," Mr Trump said. But he added: "We will have a great shot at doing a much bigger, 'maybe deal, maybe not' deal."

The two presidents repeatedly praised the relationship they have developed in the past year and said they hoped for productive talks on issues including trade, the Iran nuclear deal, North Korea diplomacy and climate change.

Mr Trump appeared to leave some room for the new sort of deal Mr Macron had proposed – saying that he could be open to a new agreement that builds on what is already in place – but made clear that any attempt by Iran to restart their nuclear program would not be tolerated.

"There is a chance, but who knows what I am going to do on the 12th," Mr Trump said, referring to the May deadline to reassure America's waiver on sanctions to Iran. "Though you have a good idea what I'm going to do."

During an earlier meeting in the Oval Office, Mr Trump said it would not be easy for Iran to restart its nuclear enrichment.

"They’re not going to be restarting anything. If they restart it, they’re going to have big problems, bigger than they ever had before,” he said.

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Speaking about potential Iran negotiations later in the Cabinet Room, he said: “We’re looking forward to doing something but it has to be done strongly."

He did not explain exactly what he meant.

The French president's three-day trip, has seen him arrive the White House for an official state visit, his first since his election last year.

After a private dinner with Mr Macron and his wife, Brigitte, with Mr Trump and First Lady Melania Trump at Mount Vernon, the home of the first US president, George Washington, the French leader was a guest of honour at a state dinner at the White House.

He is scheduled to address the Joint Houses of Congress on Wednesday.

The visit follows after Mr Trump visited France last year on Bastille Day, marking the centennial of the United States’ entry into First World War. Mr Trump was entertained by a dazzling military parade along Paris’ Champs-Élysées that included both French and American soldiers, as well as dozens of military plans and helicopters.

One of Mr Macron’s main objectives during his visit is to try and persuade Mr Trump to stay in the Iran accord, and he told reporters that he planned on framing the deal in a “wider regional context”, including the ongoing civil war in Syria.

“We have a common objective, we want to make sure there’s no escalation and no nuclear proliferation in the region,” Mr Macron said. “We now need to find the right path forward.”