Mr Khan’s address to a Fabian Society conference in central London had to be suspended for several minutes as a handful of demonstrators from the White Pendragons group called for the mayor to be arrested as they made statements in support of Mr Trump and Brexit.
When Mr Khan resumed his speech after the protesters were escorted from the venue by police, he took a dig at the American president who recently described himself as a “very stable genius”.
Mr Khan told delegates: “It is a pleasure to be here even though we were distracted by the actions of what some would call very stable geniuses.”
The mayor and US president have clashed publicly a number of times over issues like counter terrorism and Mr Trump’s proposed state visit to the UK.
The mayor also tried to make light of the protest 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.”
Video shared on social media showed the moment the activists interrupted Mr Khan’s speech, just after the mayor 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.”
Audience members started to heckle and slow-clap, during which security appeared.
However their attempts to eject those responsible for the disruption were initially met with aversion from the protesters, one of whom 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.”
He then accused the Fabian Society of “subverting” the constitution.