Dating app Bumble has banned members from posing with guns in their profile pictures, following the school shooting in Parkland, Florida.
The company said it would screen new and existing photos and remove pictures featuring weapons from the app.
However, military and law enforcement officers in uniform will be allowed to show weapons in their photos.
Bumble said it was taking "an opportunity to make our platform safer".
"As mass shootings continue to devastate communities across the country, it's time to state unequivocally that gun violence is not in line with our values, nor do these weapons belong on Bumble," the company said in a statement.
In February, 17 people were killed at Marjory Stoneman Douglas High School. Since then, survivors have campaigned for stricter gun control in the US.
Bumble says it has 30 million members worldwide, and the company already employs 5,000 moderators. They will now filter out photos of guns in addition to nudity, knives and hate speech.
However, photos displayed on a Bumble profile from a linked Instagram account will not be screened.
"Online behaviour can both mirror and predict how people treat each other in the real world. Bumble has a responsibility to our users and a larger goal to encourage accountability offline," the company said in a statement.
The app's founder Whitney Wolfe Herd acknowledged that the ban would affect law-abiding gun owners, hobbyists and hunters.
"It's a very tricky battle we've chosen to take on, but I'd rather pursue this than just ignore it," she told the New York Times.
The company has also donated $100,000 (£72,000) to the March For Our Lives campaign, which was founded by survivors of the Parkland shooting.
"We stand with them, and join them in working towards a non-violent future," the company said.