Trump: If Iran threatens US, it will pay unprecedented price

US President Donald Trump has warned Iran of "big problems" if it resumes the nuclear programme it agreed to curb in a 2015 international accord.

Speaking at the White House with French President Emmanuel Macron, Trump called the Iran deal "insane".

"It won't be so easy for them to restart," Trump said in the Oval Office when a journalist asked him about the possibility of Iran relaunching its nuclear programme if the deal is scrapped.

"They're not going to be restarting anything. They restart it they're going to have big problems, bigger than they've ever had before," BBC cited him as saying.

"If Iran threatens us in any way, they will pay a price like few countries have ever paid," Trump added.