President Donald Trump has warned Iran that it faces "bigger problems" if it restarts its nuclear programme.

Speaking at the Oval Office with French President Emmanuel Macron, Trump said the Iran nuclear deal "should never have been made."

Both leaders met in Washington to discuss the multinational nuclear agreement, the war in Syria and trade issues.

In a joint news conference, Trump told Macron he was open to "doing something" on the Iran deal as long it was done "strongly."

He suggested to Macron "we could have at least an agreement among ourselves very quickly."

However, when he was probed about what this could entail, he told reporters "you'll find out."

Making his view on the deal clear, he also said: "People know my views on the Iran deal. ... It's insane, it's ridiculous.

"It should have never been made."

It's still not clear whether the American leader is willing to remain in the current deal known as the Joint Comprehensive Plan of Action.

Those arguing for him to remain have said it has stopped Iran's nuclear programme.