After the content from Mr. Jones and his website, Infowars, was removed, he issued a plea to Mr. Trump to block the companies’ actions and “come out before the midterms and make the censorship the big issue.”

In the same video appeal, Mr. Jones urged Mr. Trump to “point out that the communist Chinese have penetrated and infiltrated” the American election system and are “way, way worse than the Russians.”

Minutes after his tweets on Saturday morning about social media, the president — who has long had an affinity for conspiracy theories — appeared to do just that.

“All of the fools that are so focused on looking only at Russia should start also looking in another direction, China,” Mr. Trump wrote. “But in the end, if we are smart, tough and well prepared, we will get along with everyone!