Between 500 and 700 demonstrators gathered in Richmond about midday on Saturday, after the location of the protest was changed from Melbourne city centre at the last minute in an attempt to evade authorities.

At one stage, dozens of people ran at police in a clash that saw officers knocked to the ground and protesters doused with capsicum spray.

Police Association of Victoria secretary Wayne Gatt described the rally as "horrific" and said 10 police were injured, including six who were taken to hospital.

"Significant violence confronted those individuals, we had bottles thrown at their faces; projectiles and rocks. This group came to assault the police," he told 3AW radio on Sunday.

"There's a range of injuries from dislocated shoulders, torn pectorals, broken bones (and) noses."

Mr Gatt said the riot squad was not deployed to help uniformed officers in Richmond, despite being in the city on standby.

"They are discussions that we will have with Victoria Police," he said.

"We'll do work in the coming days and during the coming hours just to work out what happened and why those decisions were taken, because the last thing we want is our members to go home with serious injuries."

He said the chief commissioner's decision to shut down public transport on Saturday morning was the right one.

"Had he not taken that decision, our members would have been confronted with thousands upon thousands of protesters, and those scenes would have been amplified," Mr Gatt said.

Asked about a video circulating on social media appearing to show police pushing over an elderly woman and pepper-spraying her while she lay on the road, he said he had not yet seen the vision.

"I can't comment on it specifically. I'm not going to allow my members to be criticised for the actions of these criminals yesterday, they did the best they could," he said.

Premier Daniel Andrews thanked police for doing an "outstanding" job and wished the officers in hospital well.

"No one has a right to selfishly put somebody else in hospital, whether it's through spreading the coronavirus or by violently bashing a member of Victoria Police," he told reporters on Sunday.

"This is not a popularity contest, it's a pandemic and protests don't work against this virus."

Opposition Leader Matthew Guy urged Victorians to "take your frustrations out at the ballot box at the next state election".

"The behaviour that we've seen was ridiculous and most Victorians would just shake their head in shock that that's occurred in our city," he said.

Australian Associated Press