Angry protesters have burnt placards and exchanged abuse in clashes between Reclaim Australia and anti-racism rallies in Melbourne.

At least four people have been arrested and dozens sprayed with capsicum spray, which was widely deployed during the four-hour protests on Saturday.

Hundreds of police blocked streets in front of Parliament House, separating the opposing groups.

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Small groups of protesters from Reclaim Australia and the United Patriots Front were outnumbered by anti-racism protesters representing Rally Against Racism and United Against Islamophobia.

Police say organisers were pulled aside and warned their behaviour was close to crossing the line into inciting hatred, a criminal offence.

Assistant Commissioner Stephen Leane said a small number of hardline protesters had gone along with the intention of using violence against each other and police.

“I think the message of the day from either side has been lost and I think they need to sit back and think about that,” he said.

Both the government and opposition condemned the violent scenes.

Shermon Burgess, a reputed member of the Australian Defence League who runs the Great Aussie Patriot website, said the Muslim community had to “clean its mosques” and stop radicalisation.

“We do not want a White Australia policy, we want a safe Australia policy,” he said.

Other Reclaim Australia and United Patriots Front protesters said halal certification was a stepping stone to allowing sharia law in Australia.

Coalition Against Racism and Fascism spokeswoman Vashti Kenway said anti-racism groups had mobilised to send a message that their rivals’ views are not accepted.

“The clear message is that Melburnians aren’t going to stand for the kind of far-right racist, sexist, homophobic attitudes that have really been embodied in both the United Patriots Front and Reclaim Australia, and we’re prepared to take a stand in the city, that we’re prepared to say Melbourne is not the place for those kind of attitudes,” she said.

Deputy Premier James Merlino said the community did not like seeing ugly scenes like those witnessed in Melbourne.

“Our diversity is one of our state’s greatest strengths … it’s up to all of us to protect our diversity, celebrate it, send a message to those very small number of people that the spreading of hatred, the spreading of bigotry, is simply not tolerated,” he said.

Shadow attorney-general John Pesutto said it was disappointing the government had repealed Victoria Police’s move-on powers, which could have helped defuse volatile situations.

Victorian Greens acting leader Nina Springle said it was regrettable there was a fringe element that wanted to undermine multicultural harmony.

Ambulance Victoria said several people were treated for breathing difficulties after being sprayed with capsicum spray, including a man in his 50s who was taken to hospital.

– AAP