Jessica Guynn

USA TODAY

SAN FRANCISCO — Facebook is cracking down on private gun sales.

The Menlo Park, Calif., company said late Friday it will ban users from coordinating private sales of firearms on the social network and on mobile app Instagram. The ban does not apply to licensed gun dealers for purchases completed off Facebook.

President Obama and state attorneys general have increased pressure on Facebook to tighten restrictions on firearms because of the proliferation of posts that offer guns for sale, often without background checks.

Facebook and Instagram users will no longer be able to offer or coordinate the private sale of firearms, gun parts and ammunition, the company said. That brings firearms in line with Facebook's ban on the private sales of marijuana, pharmaceuticals and illegal drugs.

Users can't buy and sell guns on Facebook itself but gun enthusiasts often connect there and sometimes make arrangements to buy, sell and trade guns.

In March 2014, Facebook took steps to limit sales of firearms including blocking minors from seeing posts about gun sales and trades and by requiring Facebook pages primarily used to promote the private sale of regulated goods and services to include language that reminds users to comply with laws and regulation.

At the time, an investigation by the technology blog VentureBeat found that adults and children were connecting on Facebook pages devoted to guns to buy, sell and trade firearms, sometimes in violation of federal and state gun laws.

Federal law enforcement sources told VentureBeat that Facebook, Instagram and other social media services were "emerging threats for unlawful gun transactions in the United States."

Moms Demand Action for Gun Sense in America and Mayors Against Illegal Guns, the group backed by former New York Mayor Michael Bloomberg, had stepped up their demands for changes to Facebook's policies after gun arrests were tied to sales of guns facilitated through Facebook.

"Over the last two years, more and more people have been using Facebook to discover products and to buy and sell things to one another. We are continuing to develop, test, and launch new products to make this experience even better for people and are updating our regulated goods policies to reflect this evolution," Monika Bickert, Facebook's head of product policy, said in an emailed statement.

Follow USA TODAY senior technology writer Jessica Guynn@jguynn