Khan was delivering a speech at a Fabian Society conference in London on Saturday when protesters disrupted his talk, according to reports.
The protesters were from a group called the White Pendragons. They were hiding in the audience and started holding up American flags when the mayor started speaking. They called for Khan to be arrested, reportedly referencing his religion, Islam.
Khan’s address had to be suspended briefly as a result of the incident.
On Friday, Khan said that Trump had “got the message” that he was “not welcome in London” after the US president canceled a planned state visit to the UK.
“President Trump got the message from the many Londoners who love and admire America and Americans but find his policies and action the polar opposite of our city’s values,” Khan said in a statement issued on Twitter.
The mayor said the US leader’s visit would “without doubt have been met with mass peaceful protests.” He added that British Prime Minister Theresa May made a mistake by inviting him on a state visit.
Trump was expected to make his first trip to the UK since entering the White House and had originally been scheduled for a full State Visit including a Royal banquet at Buckingham Palace but this was later downgraded to a “stripped-down” trip that did not involve getting the full “red-carpet” treatment from the Queen.
One senior source suggested to the Daily Mail that Trump had cancelled the trip because he was unhappy about the arrangements and the scale of the visit.
Trump had previously expressed concern about the likelihood of mass protests in a potential trip. Last year he told May that he did not want to go ahead with a visit until the British public supported it.
The intention was to repeat the success of Barack Obama’s visit to Britain in 2011, but critics pointed out the convention was to wait for a president’s second term in office before being granted the honor.
The prospect of mass protests were raised last month after the Labour Party leader Jeremy Corbyn urged his followers to turn out in force if Trump visited the UK to send him a “clear message.”
More than a million people signed a petition last year calling for the state visit to be cancelled.