Britain, Germany and France urged the United States not to take steps that would make life harder for other countries that still wanted to stick to the nuclear deal with Iran that US President Donald Trump said he was withdrawing from on Tuesday.

"We urge the US to ensure that the structures of the JCPOA (deal) can remain intact, and to avoid taking action which obstructs its full implementation by all other parties to the deal," the leaders of Britain, Germany and France said in a joint statement provided by Prime Minister Theresa May's office.

May spoke by telephone with France's President Emmanuel Macron and Germany's Chancellor Angela Merkel after Trump made his statement and the United States said it intended to reimpose sanctions on Iran.