Democratic Newsom is one of Trump's most vocal critics and has accused the president's administration of curbing basic freedoms in the United States.

"It's time to investigate. I am launching a review into whether TikTok is violating state law by censoring Trump-critical content," Newsom posted on X.

TikTok announced last week it had established a new joint venture to operate its US business, which would reduce its Chinese ownership to 19.9 percent and puts majority control in the hands of American businesses including Trump's allies.

Washington has long sought to tighten control on TikTok, citing national security concerns over the platform's Beijing-based parent company ByteDance.

"Following TikTok's sale to a Trump-aligned business group, our office has received reports -- and independently confirmed instances -- of suppressed content critical of President Trump," Newsom's office wrote on social media platform X.

Newsom shared a screenshot appearing to show a TikTok user unable to send a message reading "epstein" because it violated the platform's community guidelines.

Trump's past friendship with sex offender Jeffrey Epstein has brought intense scrutiny on the president.

TikTok did not immediately reply to a request for comment.