Speakers at the main protest expressed anti-immigration sentiments and spoke in favour of freedom of speech.
As part of the event Musk had a conversation with Robinson during which he made his controversial comments.
Musk said: “I think there’s something beautiful about being British and what I see happening here is a destruction of Britain, initially a slow erosion but rapidly increasing erosion of Britain with massive uncontrolled migration.
“This is a message to the reasonable centre, the people who ordinarily wouldn’t get involved in politics, who just want to live their lives.
“They don’t want that, they’re quiet, they just go about their business.
“My message is to them: if this continues, that violence is going to come to you, you will have no choice.”
Asked about his comments in Parliament, Mahmood said Britain was “a tolerant country and yes, we are a diverse country”.
“You can be English with roots that stretched back a thousand years.
“But you can also be English and look like me.”
Earlier, a Downing Street spokesman echoed Mahmood’s comments saying: “The last thing the British people want is this sort of dangerous and inflammatory language which threatens violence and intimidation on our streets.
“I don’t think the British people will have any truck with that kind of language and rightly so.”
Asked if the government would review its use of X, the spokesman said government communications were always kept under review.
The Liberal Democrats have called on the government to rule out awarding contracts to Musk’s Tesla company which produces electric vehicles, batteries and solar panels.
Taking questions at a press conference on Monday, Reform UK leader Nigel Farage was also asked about Musk’s language.
He said there was a “degree of ambiguity” in his words but added: “If the fight that Musk was talking about was about standing up for our rights and free speech, if it was about fighting in elections to overcome the established parties, then that absolutely is the fight that we’re in.”
Musk had previously expressed support for Farage and had reportedly been in talks over donating money to the party.
However, earlier this year he appeared to cool on the idea, saying Farage “doesn’t have what it takes” to lead the party.