The senator posed multiple questions to Zuckerberg, including asking what steps Facebook is taking to prevent abuse and whether politicians will be allowed to "correct the record" of ads as required by the Honest Ads Act.
"Facebook's apparent lack of foresight or concern for the possible damages caused by this policy concerns me," Warner said in the letter Monday.
Watch this: Zuckerberg gets grilled on Capitol Hill
Facebook has been criticized in recent weeks after it said it wouldn't be fact-checking political ads. Last week, Zuckerberg spoke in front of the House Financial Services Committee and was grilled about the company's policy. Even Facebook employees aren't happy with the policy -- more than 250 signed a letter criticizing the decision on political ads.
Facebook didn't immediately respond to a request for comment.