Andrew Bolt hits out after glitter attack

A man who witnessed part of a fight between commentator Andrew Bolt and two protesters in Melbourne says the glitter bombing was "disturbing".

Two masked men ran up to Bolt and tossed a concoction of glitter, dye and shaving cream on him from either side, as he approached restaurant Il Gambero in Carlton on Tuesday about 12.40pm.

But they apparently soon left with their tails - and a few bruises - between their legs as Bolt punched and kicked his attackers.

Local trader Paul Eliopoulos rushed from his shop when he heard the crashing of tables and chairs.

"I know he's a controversial figure and, whether you agree or not, you should be able to stand up and say 'Hey I don't agree with you, mate'," the hi-fi retailer told AAP.

"That's taking it to a completely different level and it's disturbing."

Tossing glitter at political leaders, known as glitter bombing, has frequently been used to target those opposed to same-sex marriage and other LGBTQI issues.

"He's got in a few good punches and a kick (between the legs)," restaurant owner Xavier Dimattina told AAP on Wednesday.

"It all happened very quickly."

A woman who asked Bolt for a selfie just before the attack was bowled over and shaken up by the incident but otherwise okay, Mr Dimattina said.

The 57-year-old conservative columnist labelled his attackers "leftist fascists" and posted about the fight on his blog.

"Luckily the cameras do not capture me kicking one between the legs," Bolt posted late on Tuesday.

"I cannot have my children see me acting like a thug."

After wiping blue dye from his face and assuring bystanders the red liquid on his chest wasn't blood, Bolt cleaned himself up and delivered a speech at the launch of a Donald Trump-themed book.

Victoria Police say the two men were wearing hooded jumpers and were believed to have thrown shaving cream and glitter.

Another man is shown on the video capturing the incident on camera, before the three men ran off to join a woman across the road.