Hollywood director Quentin Tarantino has hit back at police groups threatening to boycott his upcoming film, saying he stood by his comments about police brutality and would not be intimidated.

Pulp Fiction and Reservoir Dogs director Tarantino, 52, told the Los Angeles Times law enforcement groups were trying to bully him.

"Instead of dealing with the problem of police brutality in this country, better they single me out," he said.

"And their message is very clear. It's to shut me down. It's to discredit me. It is to intimidate me. It is to shut my mouth, and even more important than that, it is to send a message out to any other prominent person that might feel the need to join that side of the argument."

At an anti-police brutality rally in Brooklyn, New York, last month, Tarantino said he was "on the side of the murdered".

Those comments provoked outrage from a growing number of police groups that have called for the boycott of Tarantino's December release The Hateful Eight.

They include the National Association of Police Organisations and local bodies in New York, New Jersey, Los Angeles, Chicago and Philadelphia.

"Tarantino lives in a fantasy world," Los Angeles police chief Charlie Beck said. "That's how he makes his living. His movies are extremely violent but he doesn't understand violence. He doesn't understand the nature of the violence that police officers confront. Unfortunately he mistakes lawful use of force for murder and it's not."