TORONTO (AP) _ Saying Canadians are fed up with gratuitous violence on television - mostly coming from the United States - the national regulatory agency is urging viewers to change the channel.

The Radio-Television and Telecommunications Commission, in a report Wednesday, suggested a link between exposure to television mayhem and violence in society. It also urged broadcasters to shun especially violent programs.

''While our report indicates that there is a link, although not necessarily one of cause and effect, between television violence and violence in society, common sense also tells us that this must be true,'' said the commission's chairman, Keith Spicer.

The commission acknowledged it had limited powers to control the content on television, but said ''it wants to do whatever it can to reduce'' violence on TV.

''We have no wish to become censors,'' Spicer told The Canadian Press news agency. ''What we're hoping for is a long-term peaceful backlash.''

The ultimate weapon, he said, is for viewers to simply to switch channels when programs are too violent.

U.S. television shows flood into Canada on cable and broadcasts from border cities such as Detroit and Buffalo, N.Y. The government-owned network, the Canadian Broadcasting Corporation, also carries many American programs.

The 250-page report, entitled ''Scientific Knowledge about Television Violence,'' was based on more than 200 studies about TV violence and its effects on behavior.

The commission is working with the Canadian Association of Broadcasters to revise its code to take into consideration concerns over violence. The commission also is asking pay television movie services to cut down on violence.

Spicer urged video stores to reduce their stocks of violent movies.

He said he wanted ''to create a public mood against violence on TV that will make it unacceptable.''

The report was issued as another anti-violence campaign was picking up steam.

Thirteen-year-old Virginie Lariviere of St. Polycarpe, Quebec, has launched a petition to collect signatures of 1 million people urging legislation to curb violence on TV. The girl began the effort after her 11-year-old sister was raped and murdered last year, and hopes to present the petition to Prime Minister Brian Mulroney by the end of October.