The resolution was introduced by Supervisor Catherine Stefani on July 30, two days after a shooting at a garlic festival in Gilroy, Calif., in which three people were killed and more than a dozen others injured.
Before the resolution was put to a vote on Tuesday, Ms. Stefani spoke about the “carnage across this country,” also citing mass shootings last month in El Paso; Dayton, Ohio; and near Odessa, Tex.
Ms. Stefani said the N.R.A. conspires to limit gun violence research, restrict gun violence data sharing and block every piece of sensible gun violence prevention legislation proposed at local, state and federal levels.
While the resolution has no practical effect, Ms. Stefani said in an interview on Wednesday, “I firmly believe that words matter, and I think this is a step in fighting the negative impact of the N.R.A.”
The N.R.A. saw the action as a publicity stunt.
“This is just another worthless and disgusting ‘sound-bite remedy’ to the violence epidemic gripping our nation,” Amy Hunter, a spokeswoman for the association, said in a statement on Wednesday. “This is a reckless assault on a law-abiding organization, its members, and the freedoms they all stand for. We remain undeterred, guided by our values and belief in those who want to find real solutions to gun violence.”
The N.R.A. also responded on Twitter, saying that it was “the fabric of American society” and “San Fran should be ashamed.” The post included a video of Wayne LaPierre, the organization’s chief executive, calling on N.R.A. members to stand up as Americans.
In a news release on Wednesday, Ms. Stefani referred to the federal Justice Department’s definition of terrorist activity, which involves the use of a firearm, weapon or dangerous device to endanger the safety of individuals. The definition also includes members of organizations that provide funds, weapons or training to individuals who commit terrorist acts.
The city’s lawmakers unanimously passed the resolution in response to recent mass shootings. The National Rifle Association called it a worthless “sound-bite remedy.”