Hundreds of activist mothers marched across the Brooklyn Bridge on Saturday afternoon for a rally devoted to passing tighter restrictions on guns.

Held the day before Mother’s Day, the Moms Demand Action for Gun Sense in America rally pressed for new rules, such as background checks for mental illness and a criminal record on all gun purchases; there are now exceptions, such as on purchases from private sellers.

“This is not a Second Amendment issue!” actress Julianne Moore said of the groups’ aims, from a stage at the tip of City Hall Park in Lower Manhattan. “It does not deserve to be hotly debated as such! It is a safety issue!”

Funding for the rally came in large part from former Mayor Michael Bloomberg, the billionaire media mogul who has given tens of millions of dollars of his own fortune to lobbying efforts advocating stricter gun laws.

Many of the signs waved at the rally, the fourth annual, offered subtle rejoinders to arguments advanced by gun-rights supporters such as the National Rifle Association.

“Nobody carrying loaded guns in public is a ‘good guy,’ ” one sign read, a reference to a comment by Wayne LaPierre, chief executive of the National Rifle Association, after 2012’s Newtown shootings left 28 dead that the “only way to stop a bad guy with a gun is with a good guy with a gun.”

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Yael Denbo of Manhattan’s Upper West Side wore a red cape and rallied with her husband, son, 7, and daughter, 5.

“Gun sense & 2A can coexist,” read Denbo’s sign, referencing the Second Amendment and provided by rally organizers.

Denbo, 43, said she felt compelled to volunteer after the Newtown shootings, in which 20 of the dead were first-graders.

“I have kids so I felt like everybody’s kids are all our responsibilities,” she said.

Another sign alluded to the language of the Second Amendment, which protects the constitutional right to bear arms and “a well regulated militia”: “You want to talk well regulated militia? Meet the moms!”

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Also speaking at the rally was Barbara Parker, whose daughter Alison Parker, a 24-year-old TV reporter, was shot dead last year with her cameraman live on the air in Virginia by a disgruntled former colleague.

“You know that unless there’s change it can happen to you,” she said.

The city’s public advocate, Letitia James, faulted Congress for being “so resistant to reasonable and responsible gun laws.”

“I believe if anyone’s gonna make a difference in this country, it’s going to be moms, demanding action,” she said.

NRA spokesman Lars Dalseide said in an email Saturday that “while some groups may jump at the chance to politicize tragedies, experience tells us that real solutions to real problems are only found when relying on facts, and the fact is that criminals obtain their firearms through illegal means. ”