The Second Chance on Shoot First campaign aims to reform or repeal laws that allow the use of deadly force when someone believes they are in a life or death situation or could suffer massive bodily harm.
Bloomberg said this type of legislation gives citizens "a license to murder" and provokes "vigilante justice."
"The laws are not the kind of laws a civilized society should have and the [NRA] should be ashamed of themselves," scolded Bloomberg at a press conference in Washington, D.C. "This has nothing to do with gun-owners’ rights. This has nothing to do with the Second Amendment."
More than 20 states have a so-called "Stand Your Ground" law in place, including Florida where 17-year-old Trayvon Martin was killed in February.
Weeks after growing outrage and protests across the country, today special prosecutor Angela Corey announced a second-degree murder charge against George Zimmerman over the deadly incident. At the time of the murder, local police didn't press charges against him, citing the law.
The National Urban League, the NAACP, the National Action Network and ColorOfChange.org also support the effort.