Trump had signed an order in early April to keep TikTok running for an additional 75 days after a potential deal to sell the app to US owners was put on hold.

"Probably yeah, yeah," he responded when asked by reporters on Air Force One whether the deadline would be extended again.

"Probably have to get China approval but I think we'll get it. I think President Xi will ultimately approve it."

He indicated in an interview last month with NBC that he would be open to pushing back the deadline again.

If announced, it would be the third time Trump has extended the deadline.

The first one was through an executive order on January 20, his first day in office, after the platform went dark briefly when the ban approved by Congress - and upheld by the US Supreme Court - took effect. 

The second was in April, when White House officials believed they were nearing a deal to spin off TikTok into a new company with US ownership, which fell apart after China backed out following Trump's tariff announcement.

It is unclear how many times Trump can - or will - extend the ban as the US government continues to negotiate a deal for TikTok, which is owned by the Chinese company ByteDance. 

Trump has amassed more than 15 million followers on TikTok since joining the platform last year, and he has credited it with helping him gain traction among young voters. 

He said in January that he has a "warm spot for TikTok".

With AAP.