Nigel Farage said he had endured years of disruption from extreme leftists similar to that which faced Jacob Rees-Mogg.
The former Ukip leader castigated protesters who interrupted a university debate speech by the Tory MP.
A group allegedly broke into Friday's event at the University of the West of England in Bristol and hurled insults at the Conservative.
Mr Farage said: "It is a very extreme leftist group of people, very well-funded."
He added: "It is this intolerance of view that says, not I disagree with you, but I don't think you are entitled to voice those opinions.
"So I had years of it, literally years of it."
Video footage posted to social media captured the scenes as Mr Rees-Mogg, who has been tipped as his party's next leader, appeared to step in to separate rivals as onlookers called for them stop.
According to one witness the MP was "pushed and shoved" as a tussle broke out and police are probing the incident.
Mr Rees-Mogg said he chose to engage with the protesters because he "knew they weren't going to hit me".