Prime Minister Julia Gillard has strongly condemned violent Muslim protests on the streets of Sydney, saying they were against the Australian way of life.

Six police officers were injured on Saturday.

In Brisbane yesterday for a Labor Party state conference, Ms Gillard said she absolutely condemned the riots. ''We saw disgraceful conduct. There is never any excuse for violent behaviour,'' she said.

''To anybody who wants to replicate that behaviour today I want to say very strongly, this kind of conduct has got no place on the streets of our country.

''I also want to say very clearly, I do not want to see in the hands of anyone, particularly children, offensive signs that call for the killing of others. This is not the Australian way.''

The Prime Minister described the anti-Islam film as ''truly repulsive'' but said there was no excuse for the violent reaction seen in Sydney.

''We believe in freedom of religion and we believe that every religion should be treated with respect,'' she said.

NSW Police Commissioner Andrew Scipione expressed outrage that children were holding offensive signs at the rally, adding that ''extremist offenders'' had turned a peaceful protest by about 300 people into a violent riot.

''To see a young child with a placard thrust in his hand calling for the beheading of a person is simply something I cannot comprehend,'' the commissioner said.

''It's just not what we teach our children.''

Opposition Leader Tony Abbott said the protests were appalling, but were not a true reflection of the Australian Islamic community. He said all Australians should send a strong message to the campaigners that violence is not acceptable in protests.

''And we expect every Australian to live in accordance with Australian values,'' Mr Abbott said.

''Newcomers to this country are not expected to surrender their heritage, but they are expected to surrender their hatreds.''

Mr Abbott also repeated his call for British Muslim leader Taji Mustafa's Australian visa to be revoked, describing him as a ''preacher of hate''.

But Ms Gillard said the group Mr Mustafa was addressing in Australia yesterday, Hizb ut-Tahrir, was not a proscribed terrorist organisation in this country, nor was it in the United Kingdom or the United States.