Victoria's top police officer has issued a passionate defence of migrant communities, as Bendigo braces for furious anti-Islam protests on Saturday, and far-right militants threaten to target mosques around the country in co-ordinated protests on the same day.

In a rare foray into public debate, Police Commissioner Graham Ashton said police would not tolerate protesters who targeted particular religious groups.

"Our reputation for warmth and generosity is increasingly at risk from a new wave of intolerance that appears to be gaining traction in some parts of the country," Mr Ashton wrote in an opinion piece published in The Age today.

"Now, more than ever, is the time for Victorians of all faiths to be standing together, and focusing on the common bonds and values which unite us, not the points of difference on which ignorance can prosper and fuel division."

Nationalist, far-right and neo-Nazi groups are planning to converge on Bendigo on Saturday, to protest the regional city council's approval of plans for a new mosque.

The city has become a flashpoint for far-right discontent over a raft of issues, including Australia's immigration policies, fears of terrorism and Halal food, multiculturalism and "lefties".

Creating a further security headache for authorities, the Bendigo protest coincides with the so-called "global rally for humanity" rallies, which call on people to protest against Islam and Muslim migration at their local mosques, in co-ordinated protests.

They have been heavily promoted among Australian far-right groups, as well as in Canada, parts of Europe, and the United States where demonstrators have been urged to bring guns.

"I am in no doubt the vast majority of Victorians will be dismayed by this activity, which will require the deployment of many police to locations across the state in order to ensure the peace is kept," Mr Ashton said.

NSW Police confirmed they are investigating extreme nationalist group the Australian Defence League over a post urging followers to target Muslim leaders in "lone wolf" attacks.

"Now these scum of the Earth protest when a video gets made about the paedophile Mohammed and we are having our daughters raped and our police shot in cold blood," a Facebook post, which has since been deleted, read.

"I think its [sic] time for an eye for an eye. So let the Lone wolf attacks start on Mosques and the Imams."

But the United Patriots Front, which in August urged its followers to join the co-ordinated mosque rallies, has now distanced itself from them.

The hardline group, which has been instrumental in organising Saturday's Bendigo rally, now says it does not support other protests on the day.

"All other rallies or events within or out of Victoria are not connected to our movement and we encourage all Australian people to be vigilant and stay smart; stay away from Parramatta Mosque and let the police do their job."

Mr Ashton said there was no place for religious vilification in Victoria, and police would not tolerate any acts of violence by "the small bands of militant protesters" expected in Bendigo and elsewhere, and by counter protesters.

"They must not overstep the mark. If protesters use violence they can expect to face the consequences.

"Everyone has the right to protest. But protests should always be peaceful and in a manner which is constructive, not destructive to our community harmony which thrives on inclusivity and shuns discrimination in all its forms."

The Q Society of Australia, a secretive "Islam sceptical" group that was instrumental in the campaign against the Bendigo mosque, wrote to its members on Wednesday night to distance itself from the weekend's protests and ask them not to distribute material with Q Society logos at the rally.

"Should you decide to attend ... please be aware there is a possibility of being filmed next to placards and individuals you would normally not want to be associated with. For example Neo-Nazi groups like to infiltrate and use such events for gaining the trust of unsuspecting supporters. Rallies like these are known for attracting bullies and 'activists' looking for confrontation."