The President has once again taken aim at the Mayor of London.
Khan had said on Sunday morning that people would see an increased police presence on the streets of the capital and should not be alarmed by that.Trump mocked Khan's comment on Sunday, suggesting in a tweet that the mayor was downplaying the attacks.
A spokesman for Mr Khan, responding to Mr Trump's latest tweet, said: "Nothing has changed since yesterday".
Trump, writing on Twitter Monday, said: "Pathetic excuse by London Mayor Sadiq Khan who had to think fast on his "no reason to be alarmed" statement. MSM is working hard to sell it!" he wrote.
"I think Sadiq Khan is doing a good job and it's wrong to say anything else - he's doing a good job", she told reporters at an election campaign event in London.
May declined to directly criticize Trump for his tweet, which has prompted a fierce backlash in Britain.
Trump and Khan have spent the previous year sniping at one another, largely over Trump's proposed travel ban that would temporarily bar some Muslims from entering the United States.
Trump's criticism came a day after he said he would do whatever is necessary to protect the United States from a "vile enemy" that he said has waged war on innocents for too long, .
They said of Mr Khan: "He has risen above this crisis of death and destruction, as mayors continue to do, to alleviate fear, to bring comfort to his people of London and to give support to the first responders who continue to protect, defend and provide emergency care to his people of London".
That evening, Trump took to social media to blast Khan for his response to the attack.
Khan has pushed back, calling Trump bigoted and saying that he doesn't need advice from the president.
Khan has reportedly also said Trump was wrong about "many things" and that his state visit to the United Kingdom should not go ahead.
President Donald Trump lashed out at his own Justice Department Monday for seeking the Supreme Court's backing for a "watered down, politically correct version" of the travel ban he signed in March instead of a broader directive that was also blocked by the courts.
She replied: "I'm very clear that Sadiq is doing a good job as mayor of London".