Twitter Inc. on Tuesday suspended the far-right talk-show host Alex Jones for violating the social media company’s policies, a reversal amid intensifying public scrutiny and criticism of Mr. Jones’s posts on the platform.

Mr. Jones will be blocked from posting on Twitter for seven days because of an offending tweet, the company said. Twitter declined to comment on the content that violated its policies, but in a note to Mr. Jones it said a tweet about taking action against web censorship included a link to a video that violated...