Speaking at a joint press conference in Washington after talks with the US president, Macron said he wanted a new deal that would work for everyone.
Trump has described the landmark agreement signed by his predecessor, Barack Obama, as insane and called for it to be torn up.
"You don't rip up an agreement to go nowhere, you create a new, broader one," Macron said, adding that subjects such as the conflict in Syria, where Tehran supports Bashar al-Assad's government, could be addressed.
"I think we will have a great shot at doing a much bigger, maybe, deal," the US president said, while insisting that any new agreement must be built on "solid foundations" and adding Yemen and "other parts of the Middle East" to the list of subjects that should be covered.
Several European countries have repeatedly tried to persuade him not to abandon the 2015 deal, which gives Iran sanctions relief and the guarantee of a civilian nuclear programme in return for limiting enrichment that could produce weapons grade fuel.
The German Chancellor Angela Merkel is expected to reinforce her support for the deal when she visits Washington on Friday.
Iran has warned it will increase its enrichment activities if Trump walks away from the accord.
Signs of affection
"I like him a lot," was Trump's judgement on his French counterpart after talks that lasted longer than scheduled, and he showed certain signs of affection towards his visitor, hugging him and brushing dandruff off his jacket.
Macron has urged him to extend the current exemption for the European Union, which comes up for review on 1 May, but the US leader insists that previous trade terms were unfair.
"We have both understood that we do not have the sort of temperaments that allow us to change opinions easily," Macron commented but he claimed there had been "real advances", without going into details as to what they might be.
Speech to Congress
Macron was to address a joint meeting of both houses of Congress in English on Wednesday, the 58th anniversary of when French post-war leader General Charles de Gaulle did so.
He was expected to speak about the environment, growing inequality, terrorism, threats to democratic values and the rise of nationalism.
Later in the day he was due to speak to a group of American students, an exercise he is reportedly fond of, having done the same during trips to Burkina Faso and India.
At least one person back home has been impressed by Macron's performance in Washington.
The president is "up to the job and the historic mission that is his today"; François Bayrou, the leader of the liberal Modem party which supports the government, said on Wednesday.
"What is new is new and what is great about what is happening today on the world stage, and in Washington at the moment, is that we are hearing a different voice of France ... a mediating voice," Bayrou told CNews TV.
Macron is not "defending France's selfish interests, not a vision of French domination but ... an idea of a new world order, an idea of a common interest of the world".