Australians warned against retribution

Australians have been warned against taking to the streets in response to the biggest counter-terrorism raid in the nation's history.

A "high visibility" police operation has been launched for busy Sydney streets, transport hubs, iconic locations and critical infrastructure.

"It will be ... happening in areas where potentially people may want to either take some retribution or in fact create trauma within communities," NSW Police Commissioner Andrew Scipione told reporters in Sydney today.

"We won't be tolerating any misbehaviour on the streets."

Operation Hammerhead will include more than 220 officers "very visible, out and about".

Mr Scipione said people should remain calm but vigilant.