"We're banning them from the United States," Trump said.
The app, which allows users to film and share short videos of themselves along to accompanying music, is owned by the Chinese company ByteDance. The relationship has caused the Trump administration, as well as lawmakers across both aisles, to accuse the app of being a security threat
The president said he would sign something as soon as Saturday, without specifying whether he was going to act through an executive order. Trump called the decision "severance" and firmly rejected the reported spinoff deal involving Microsoft buying TikTok.
When asked for comment, a TikTok spokesperson told ABC News: "These are the facts: 100 million Americans come to TikTok for entertainment and connection, especially during the pandemic. We've hired nearly 1,000 people to our U.S. team this year alone, and are proud to be hiring another 10,000 employees into great paying jobs across the US. Our $1 billion creator fund supports U.S. creators who are building livelihoods from our platform. TikTok U.S. user data is stored in the U.S., with strict controls on employee access. TikTok's biggest investors come from the U.S. We are committed to protecting our users' privacy and safety as we continue working to bring joy to families and meaningful careers to those who create on our platform."
TikTok has an estimated 65 million to 80 million users in the United States.
The American Civil Liberties Union, a New York City-based nonprofit advocacy organization, said banning an app like TikTok "is a danger to free expression and technologically impractical."
Trump threatened to ban the app while speaking to reporters before leaving for Florida earlier in the day, but did not commit to any specific actions, saying, "We're looking at TikTok, we may be banning TikTok."
"We’ll see what happens, but we're looking at a lot of alternatives with respect to TikTok," the president said.
The Chinese video-sharing social networking service hasn't just triggered fear among Republicans. The Democratic National Committee also warned members against using TikTok earlier this month, according to an email obtained by CNN.
Earlier this month, a TikTok spokesperson told ABC News that the company is "led by an American CEO, with hundreds of employees and key leaders across safety, security, product, and public policy here in the U.S. We have no higher priority than promoting a safe and secure app experience for our users."
On July 15, Trump's chief of staff Mark Meadows said, "There are a number of administration officials who are looking at the national security risk as it relates to TikTok, WeChat and other apps that have the potential for national security exposure, specifically as it relates to the gathering of information on American citizens by a foreign adversary."
The United States would not be the first major country to ban TikTok. India banned the app in late June.
ABC News' Alexandra Faul and Morgan Winsor contributed to this report.