TikTok has touted a complex plan known as Project Texas to help ease U.S. concerns over its ownership.
After two years of negotiations with the Committee on Foreign Investment in the United States, or CFIUS, the White House reportedly demanded last week that ByteDance sell TikTok.
On Thursday, a Chinese commerce ministry spokeswoman said, "If the news is true, China will resolutely oppose it."
TikTok became a viral sensation in the U.S. by allowing young people to create and share short videos.
But the company announced this week that it has 150 million users in the United States, a figure that, if confirmed, amounts to nearly 60% of the population.