Mr Khan’s address to a Fabian Society conference in London was interrupted by activists moments after he was introduced to the stage.
One man could be heard addressing the audience with: “Ladies and gentlemen, we’re here today to make a non-violent, peaceful citizen’s arrest.”
The address had to be suspended for several minutes and the demonstrators, from a group called the White Pendragons, were later escorted from the venue by police.
As attempts were made to eject them, one of the protestors could be heard saying: “We stand under Common Law jurisdiction.
“If you touch us, you’ll be done for common assault. Please stand back, do not touch us. We’re not leaving, we’ve paid for a ticket.”
When he resumed his speech Mr Khan made light of the incident with a reference to Prime Minister Theresa May’s Tory conference speech which was interrupted by a prankster, saying: “On the plus side I wasn’t served with a P45.”
And in a dig at the US president, the London Mayor said: “It is a pleasure to be here even though we were distracted by the actions of what some would call very stable geniuses.”
The incident comes just a day after Mr Khan said President Trump had “got the message”, hence the cancellation of his visit to London.
He said: “It appears that President Trump got the message from the many Londoners who love and admire America and Americans but find his policies and actions the polar opposite of our city’s values of inclusion, diversity and tolerance.”
Many Londoners have made it clear that Donald Trump is not welcome here while he is pursuing such a divisive agenda. It seems he’s finally got that message. pic.twitter.com/YD0ZHuWtr3
— Sadiq Khan (@SadiqKhan) January 12, 2018