A Downing Street spokesperson said:
The Prime Minister held a telephone call with US President Donald Trump this evening.
The Prime Minister began by congratulating the President on the safe return of three US citizens who had been held in prison in North Korea.
The two leaders looked forward to the summit which will take place between President Trump and Kim Jong-un in Singapore. The PM said the UK would continue to work with the US to keep up the pressure on North Korea to denuclearise.
The Prime Minister and the President condemned the Iranian rocket attacks against Israeli forces earlier this week, and strongly supported Israels right to defend itself against Iranian aggression. They agreed on the need for calm on all sides and on the importance of tackling Irans destabilising activity in the region.
The Prime Minister reiterated the Governments position on the Iran nuclear deal, noting that we and our European partners remain firmly committed to ensuring the deal is upheld, as the best way of preventing Iran from developing a nuclear weapon.
The Prime Minister raised the potential impact of US sanctions on those firms which are currently conducting business in Iran. They agreed for talks to take place between our teams.
Finally, the Prime Minister and the President looked forward to the Presidents visit to the UK in July.