It has become the first Chinese-owned social media platform to attract a mass following in western countries, where the app is used by tens of millions of teenagers to share viral dance routines, sketches and lip syncing videos.
However, opaque rules on how it collects sensitive user data have fuelled fears it could be used by Beijing as a surveillance tool or for propaganda purposes. India has already barred the TikTok app over national security and privacy concerns while other countries are reportedly mulling similar measures.
TikTok has said all its data is stored in servers in the US and insisted it would not remove content even if asked to do so by the Chinese government.
It has also denied handing over data to Chinese authorities and has taken steps to separate its app from its Chinese parent company ByteDance.
In June it took a major step toward burnishing the service by hiring ex-Disney streaming boss Kevin Mayer. Mayer, who runs TikTok globally, is hoping to smooth relations with US lawmakers.
Pompeo's comments on a ban were made ahead of TikTok's announcement that it would stop operations in Hong Kong, where it has 150,000 users, joining other social media companies in eyeing ramifications of a sweeping national security law that took effect last week.
Tech giants, including Facebook, Twitter, Microsoft and Zoom, say they are assessing implications of the security law, which prohibits what Beijing views as secessionist, subversive or terrorist activities or as foreign intervention in the city's internal affairs.
Many of these Western technology firms, such as Facebook and Twitter, are already banned in mainland China given strict government censorship and control of news, information and social media.
"The Chinese Communist Party's destruction of free Hong Kong continues," Pompeo said in a sharply worded statement.
"With the ink barely dry on the repressive national security law, local authorities - in an Orwellian move - have now established a central government national security office, started removing books critical of the CCP from library shelves, banned political slogans, and are now requiring schools to enforce censorship."
Pompeo condemned what he called the "latest assaults on the rights and freedoms of the people of Hong Kong".
"Until now, Hong Kong flourished because it allowed free thinking and free speech, under an independent rule of law. No more."
