US President-elect Donald Trump says he would "most likely" give the popular social media app TikTok a 90-day reprieve from a potential ban in the United States after he takes office.

Trump spoke in a phone interview with NBC News on Saturday, one day before a law banning the video-sharing platform is scheduled to take effect.

Trump said, "The 90-day extension is something that will be most likely done, because it's appropriate. We have to look at it carefully."

But it remains unclear on what grounds Trump plans to delay the enforcement of the law after it comes into effect.

White House Press Secretary Karine Jean-Pierre issued a statement on Saturday, reiterating the plan of President Joe Biden's administration not to implement the law immediately.

The spokesperson said, "We see no reason for TikTok or other companies to take actions in the next few days before the Trump Administration takes office on Monday."

The law will prohibit IT firms from providing downloads and updates of TikTok in the US unless its China-based parent company, ByteDance, sells it by the time the legislation comes into force. The Supreme Court upheld the law on Friday.

US media say it remains to be seen whether TikTok services will become unavailable on Sunday.