It urged CEO Shou Zi Chew in a letter to "urgently step up" efforts, and spell out "within the next 24 hours" how it is complying with European law.
Social media firms have seen a surge in misinformation about the conflict, including doctored images and mislabelled videos.
The EU previously warned X, formerly Twitter, and Meta about such content.
It said TikTok needed to be mindful of its popularity with young people.
