TikTok is threatening legal action against the US after Donald Trump ordered firms to stop doing business with the Chinese app within 45 days.
The company said it was “shocked” by an executive order from the US President outlining the ban.
TikTok said it would “pursue all remedies available” to “ensure the rule of law is not discarded”.
Mr Trump issued a similar order against China’s WeChat in a major escalation in Washington’s stand-off with Beijing.
WeChat’s owner, Tencent, said: “We are reviewing the executive order to get a full understanding.”
As well as WeChat, Tencent is also a leading gaming company and its investments include a 40% stake in Epic Games – the company behind the hugely popular Fortnite video game.
The president has already threatened to ban TikTok in the US, citing national security concerns, and the company is now in talks to sell its American business to Microsoft. They have until 15 September to reach a deal – a deadline set by Mr Trump.
The Trump administration claims that the Chinese government has access to user information gathered by TikTok, which the company has denied.