Some of the most prominent users of the social media platforms called for a boycott to protest Facebook's failure to control disinformation and hate speech as part of the campaign #StopHateForProfit.
The company said its new policy would eliminate search predictions that could be seen as favoring a political candidate or as making claims about "the integrity or legitimacy of electoral processes."
Twitter will label or remove posts that spread misinformation. Social media companies are under pressure to curb the spread of false claims and prevent interference from foreign and domestic actors.
Facebook's head of security policy, Nathaniel Gleicher, said that the company is working harder than ever to counteract efforts to interfere in the 2020 presidential election.
Both social networks said the president's false claims that children are "almost immune" from COVID-19 violated its policy on coronavirus misinformation.
Archaeologists have ID'ed 100-plus Facebook groups offering looted and illicit antiquities for sale. New rules ban the sale of "historical artifacts" on Facebook but critics want more enforcement.