If the protest does proceed, police are resigned to not being able to fine everyone who turns up given the impracticality of doing so.

“We don’t want it to happen,” Mr Patton said on Friday afternoon.

“We don’t want to be applying any use of force whatsoever … we don’t even want this to go ahead, but if it does we will try and have a peaceful [event], but people have to be accountable for their actions.”

“If it goes ahead we'll probably have to apply a lot of discretion because you can't practically issue thousands and thousands of infringements.”

Mr Patten said if the protest became unruly and if police were physically confronted by protesters, they would arrest attendees. Police could issue a declaration to perform searches on protesters if necessary, he said.

“We will do what we can,” he said. “My message is 'don’t go', it will be illegal because of the Chief Health Officer’s directions.

“Do it online, do it at home, post something in solidarity online.”

Meanwhile, NSW Police are taking the organisers of Sydney's simultaneous Black Lives Matter protest to the Supreme Court, after the number of people expected to join the rally swelled in the time since it was given approval.

NSW Premier Gladys Berejiklian said it "never was and never will be" the state's intention to allow thousands of people to be "flagrantly disregarding the [state's] health orders".

Prime Minister Scott Morrison also urged people not to attend protests which are planned to take place across the country.

"Our message is very clear," Mr Morrison said. "The health risks and the risks of people coming into close proximity are real, and Australians have worked incredibly hard in recent months and undergone great sacrifices to protect the health of the most vulnerable, and that has included our Indigenous communities."

Gatherings of more than 20 people are not permitted under Victoria's current regulations but more than 30,000 people have indicated they will attend or are interested in this weekend's march against police brutality.

Organisers have asked people to wear masks, bring hand sanitiser and self-isolate afterwards if they can but Dr Sutton said now was not the time to hold a protest.

"There is a risk that all of the gains that we have made are put at risk by people gathering in large numbers," he said.

"It takes a single individual who is infectious to potentially transmit to many others in a mass gathering setting.

"I am advising people not to attend. There are other ways to protest."

Dr Sutton said anyone who ignores advice to not attend should stay 1.5 metres apart and wear a mask if they can.

However, he said this would be difficult when people are protesting loudly.

"That's what protests do so that adds to my concern about the risk of transmission," he said.

There were three new COVID-19 cases in Victoria recorded overnight, taking the total number of people who have had the virus to 1681. There are currently 74 active cases in the state.

Of the new cases, two were returned travellers in hotel quarantine and one was a prep student from Newbury Primary School in Craigieburn.

The student had no symptoms last week and developed symptoms over the weekend.

The school is closed for cleaning and will reopen next week.

Mr Morrison said one of the government's biggest worries at the start of the coronavirus outbreak was the potential impact on Indigenous communities.

"This isn't about people's ability to express themselves and engage in protest activity, we all respect that," he said.

But Mr Morrison urged protesters to find another way to express their views without putting their health and that of others at risk, along with "the great gains we have been able to make as a country in recent months".

"I encourage people not to attend for those reasons and those reasons only," he said.