Mayor Bloomberg may be unwilling to criticize his predecessor directly, but he is leaving little doubt about his distaste for Mayor Giuliani’s newfound courtship of the gun lobby.

“Rudy Giuliani can speak for himself,” Mr. Bloomberg told reporters yesterday at City Hall before launching into a full-throated defense of policy positions that the former mayor has recently disavowed or opposed.

Mr. Bloomberg was responding to Mr. Giuliani’s comments last week to the National Rifle Association, in which he distanced himself from a lawsuit against firearm manufacturers that he initiated as mayor and which the city is still pressing. Mr. Giuliani also voiced support for a gun law that Mr. Bloomberg has mounted a national campaign to overturn.

The Republican presidential hopeful said on Friday that the lawsuit “has taken several turns and several twists that I don’t agree with.”

Contradicting Mr. Giuliani, Mr. Bloomberg said the lawsuit “has not changed at all” since the city filed it in 1999. “We believe that it’s a good case and we hope to win,” Mr. Bloomberg said.

The lawsuit accuses gun manufacturers of failing to supervise adequately sales practices that have led to large numbers of guns winding up in the hands of criminals. Mr. Bloomberg offered an equally staunch condemnation of the Tiahrt amendment, which Mr. Giuliani had described as “sensible” to the NRA on Friday.

The legislation, named for the Republican congressman who sponsored it, has been inserted into congressional spending bills since 2003 and places restrictions on how gun trace data can be used. “The Tiahrt amendment is something that is not in the interest of people who want to be safe in this country,” Mr. Bloomberg said. “It’s an outrage.”

The city contends that the amendment ties the hands of police in the city’s fight against illegal guns.

In his bid for the Republican presidential nomination, Mr. Giuliani has moved sharply away from the pro-gun control positions he supported as mayor.

He has more recently argued that gun laws should be decided at the state and local level, a position that Mr. Bloomberg appeared to take issue with yesterday. “For those that say gun laws and enforcement of gun laws should be the province of localities of municipalities and states, I couldn’t agree more,” Mr. Bloomberg said. “The trouble is that the Tiahrt amendment is designed to prevent that, so you can’t have it both ways. You can’t say this should be left to localities and then have a federal law that doesn’t give them the information.”

A spokeswoman for the Giuliani campaign, Maria Comella, declined comment. She also declined to elaborate on Mr. Giuliani’s position on the Tiahrt legislation or the city’s lawsuit.

Mr. Giuliani’s initiation of lawsuits against the gun industry was “courageous” and “innovative,” the legal director of New York University’s Brennan Center for Justice, Bert Neuborne, said. “As far as I am concerned, the cases are exactly the same as when they were brought,” he said. “The only twists and turns are from Giuliani.”