"Of course we review after any incident that takes place, and we have had, sadly, a number of terrorist attacks in the United Kingdom this year".
The president's intervention threatened to place fresh strain on the US-UK intelligence-sharing relationship which has come under pressure a number of times since he entered the White House.
WASHINGTON (CNN) - President Donald Trump on Friday again called for the implementation of his travel ban in the wake of an overseas terror incident, railing against "loser terrorists" behind the London Tube explosion.
Trump was accused of betraying intelligence details by saying those responsible for an explosion on an underground train "are sick and demented people who were in the sights of Scotland Yard".
May, when asked directly about Trump's tweets, responded in a broadcast interview: "I never think it's helpful for anybody to speculate about what is an ongoing investigation".
She also said that the police and security services were doing all they could to identify those responsible for the "cowardly attack".
Trump said he had been briefed on the London attack, and said he had been told about "new risks of things happening".
"It's a awful thing". And we have to be very smart and we have to be very, very tough, which perhaps we're not almost tough enough. "We have to be very, very tough". "It is a awful thing - just keeps going and going".
During the telephone call, Trump conveyed his sympathies and prayers for those injured in the attack, the White House said in a statement.
The latest spat comes after British police temporarily suspended intelligence-sharing with the USA in the wake of the Manchester Arena bombing in May following a series of leaks to American media. A hunt was on for a suspect the British media labelled as the "bucket bomber".
The normally tight-lipped agency called the allegations "nonsense", adding that "they are utterly ridiculous and should be ignored".
The president has repeatedly criticized London Mayor Sadiq Khan, the British capital's first Muslim leader.
"My priority is making sure that we do what we can to keep Londoners safe". "And to be able to take the necessary action when people do cause us harm", she said. "That's quite clear what he thinks about that".