Victoria Police say they are "disappointed" after protesters clashed with riot and mounted police outside a Melbourne venue hosting far-right Canadian provocateur Lauren Southern.

More than 100 protesters blocked the Hume Highway outside Somerton's La Mirage Reception and Convention ahead of Ms Southern's Friday night event.

At one point, the group rushed at a bus filled with attendees, slapping it and chanting "surround the Nazi bus" while being mooned by a man inside it.

The Campaign Against Racism and Fascism organised a protest against Southern. (AAP) (AAP)

Controversial far-right speaker Lauren Southern is in Australia for a tour. (AAP) (AAP)

Inside, Ms Southern's speech was interrupted by protesters with banners and chanting "racism off out streets", according to the Whistleblowers, Activists and Citizens Alliance group.

The young provocateur is known for her controversial views on multiculturalism, Islam and feminism and was banned in March from entering the UK.

The Campaign Against Racism and Fascism says Southern is "a notorious racist and Islamophobe".

Protesters have clashed with police outside a venue where Canadian far-right activist Lauren Southern is speaking in Melbourne. (AAP) (AAP)

Protesters came close enough to the bus to hit it. (AAP) (AAP)

"She is known for her involvement in the racist attempts to obstruct NGO search-and-rescue boats trying to help shipwrecked migrants in the Mediterranean," the group said in Facebook statement.

Back outside, right-wing activist Neil Erikson filmed protesters before being hauled away from police.

He and two other men are charged with affray and riot over an incident outside an event by controversial commentator Milo Yiannopoulos last year.

Southern was reportedly charged for the use of police resources. (AAP) (AAP)

On Friday night, anti-Southern protesters blocked the Hume Hwy and police attempted to subdue them with pepper spray before surrounding the group against a fence.

Victoria Police is reportedly charging Ms Southern more than $67,000 for their presence at the event.

"Their actions put their lives, the lives of the public and the lives of police officers at risk," Commander Tim Hansen said.