“There is an epidemic of gun violence plaguing our country, and we need to hold organizations like the N.R.A. accountable for their obstruction to real reforms to make our communities safer,” Ms. Breed said in a statement on Tuesday. “While this nonbinding resolution has no force of law behind it, this doesn’t take away from the fact that the N.R.A. continues to shamefully stand in the way of every single piece of gun control legislation.”

John Coté, a spokesman for Mr. Herrera, said the Sept. 23 memo was “not a concession,” adding: “It just explains what has always been true — the resolution does not change the law. If the N.R.A. thinks this is a win, it’s only because their lawsuit completely distorts what the resolution actually does.”

William A. Brewer III, a lawyer for the N.R.A., said that city officials “wisely have attempted to pull back from what we alleged, the association alleged, was a clear violation of the association’s First Amendment rights.”

But the group is not ready to drop its litigation.

“What we hope is that the Board of Supervisors will further mitigate the damage they’ve done,” he said, adding that the organization would like to see the board rescind or repeal the resolution, “or walk away from it in some binding way.”

The group considered San Francisco’s original declaration part of a series of actions against it by Democratic leaders in the wake of several mass shootings. The Board of Supervisors passed the resolution two days after three people were killed and 13 injured in a shooting at a garlic festival in Gilroy, Calif.