“The N.R.A. exists to spread pro-gun propaganda and put weapons in the hands of those who would harm and terrorize us,” Ms. Stefani said in a statement. “Nobody has done more to fan the flames of gun violence than the N.R.A.”

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.