By Georgia Wells and Jeff Horwitz

Facebook Inc. and Twitter Inc. said they were limiting the spread of what they determine to be dangerous content, as the social media platforms scrambled to tamp down commentary that could further inflame protests at the U.S. Capitol.

Twitter said Wednesday that it limited the ability of users to share a video about the protests from President Trump because of a "risk of violence" and said it was taking other measures to slow the spread of potentially dangerous content. Facebook said it was actively reviewing and removing some posts that violate its rules forbidding incitement of violence.

Twitter and Facebook have grappled with false claims about the election since November, when Mr. Trump made premature declarations of victory and claimed there was a plot to steal votes.

U.S. election officials have characterized the November election as the most secure in U.S. history. Still, the false statements from Mr. Trump and some of his supporters unleashed weeks of viral claims about attempted election theft and posts that encouraged violence.

Twitter on Wednesday reminded users in a series of messages that calls to violence are against its rules, and said it has been "significantly" restricting the engagement of tweets that threaten the integrity of U.S. institutions.

In a video posted to Twitter, Mr. Trump described the protesters as very special, called the election stolen and fraudulent and said he understands how the protesters feel. Mr. Trump also encouraged protesters to go home.

"This claim of election fraud is disputed, and this Tweet can't be replied to, Retweeted or liked due to a risk of violence," Twitter said in a note appended to Mr. Trump's video.

Twitter also said on Wednesday that it was exploring other "escalated enforcement actions" for certain posts. The company didn't elaborate on what those actions could be.

Facebook included a label on Mr. Trump's video directing users to a page with accurate election information. The company said it is actively reviewing and removing any content on its platform that breaks its rules, including incitement and calls for violence.

"The violent protests in the Capitol today are a disgrace," a spokesperson for Facebook said in a statement.

Twitter and Facebook have grappled for months with how to handle posts from Mr.Trump and his supporters related to the election, efforts that have at times reignited claims from some conservatives that the companies are censoring political content.

Others believe the companies acted too late and could have done more to limit the spread of false claims about the election that led to Wednesday's violence at the Capitol.

"These events were planned, propagated, and set into motion on social media," said John Redgrave, a cyber safety expert. "No platform can stand back and wash their hands of it because the environment that has led to this grew directly from the fertile soil of extreme, unmitigated discourse."

Write to Georgia Wells at Georgia.Wells@wsj.com and Jeff Horwitz at Jeff.Horwitz@wsj.com

(END) Dow Jones Newswires

01-06-21 1821ET