Emmanuel Macron has taken a parting shot at Donald Trump and said it is 'insane' the US is pulling out of international treaties while predicting the President would kill the Iran deal.

The French leader said Trump would get out of the nuclear agreement next month for 'domestic reasons' and accused the US of short-termism by withdrawing from treaties it had only just joined.

His comments on Wednesday come towards the end of a three-day state visit which saw Macron and Trump lavish each other with compliments and heap praise the warm relationship between their two countries.

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The French leader (left, at George Washington University on Wednesday) said Trump (right, at Tuesday's state dinner) would get out of the Iran deal for 'domestic reasons'

'My view — I don't know what your president will decide — is that he will get rid of this deal on his own, for domestic reasons,' Macron told around a dozen reporters at George Washington University.

When pressed again on whether Trump would ditch the deal, Macron replied: 'I think so. That's my view. I don't have any specific information, I'm not an insider. My view is that there is a big risk he will leave.'

And on Trump's tendency to pull out of international treaties, the French leader said: 'It can work in the short term but it's very insane in the medium to long term,' he said of the US decision 'to change [its] opposition so often.'

Trump - a fierce opponent of the July 2015 agreement signed by Tehran and international powers - must declare by May 12 if he will essentially walk away from the existing deal when the renewal deadline arrives on May 12, or stay in.

Macron had come to Washington in part to plead for a more comprehensive 'new agreement' that would address what he and Trump believe to be shortcomings of the existing accord.

Trump has branded the Iran deal 'insane' and the 'worst' in history.

Macron displayed his usual love for selfies while greeting crowds who had come to watch his George Washington University speech

The French President received a warm welcome from students, who came out in their droves to meet him

Macron waves to someone in the distance as members of the audience take photos on their phones

'I have no inside information' on what decision Trump will make on the agreement, Macron told journalists on Wednesday.

But 'I listen to what President Trump is saying and it seems to me that he is not very eager to defend it.'

Macron recalled that Trump made killing the Iran nuclear accord a campaign pledge during his 2016 presidential run.

'The rational analysis of all his statements does not make me think that he will do everything to maintain' the agreement signed with Iran to prevent the Islamic republic from acquiring an atomic bomb.

Asked whether such a decision would signify a personal failure for him, Macron stressed that his role 'is not to try to convince President Trump to walk away from his campaign commitments.'

President Trump, first lady Melania Trump, Brigitte Macron, and French President Emmanuel Macron pose for a photo in Grand Foyer before a State Dinner at the White House in Washington on Tuesday

During his state dinner toast on Tuesday, President Trump raised a glass to President Macron saying: 'May our friendship grow even deeper'

Instead he offered further defense of the deal, saying 'I'm trying to prove that this agreement makes sense.'

The proposal that Macron put forward to his US counterpart involves preserving the existing agreement on the first of 'four pillars' of a future deal.

The others would address the period after 2025, when certain clauses concerning nuclear activities will sunset; Tehran's highly controversial ballistic missile program; and its 'destabilizing' role in the region.

'For me it's progress, it avoids falling into the complete unknown if the US decision is a hard exit,' said Macron, who confirmed that the proposal was a strategy coordinated with European partners and not a unilateral one.

Trump withdrew from the Trans-Pacific Partnership last year, but has since raised the prospect of rejoining.