US President-elect Donald Trump on Sunday promised to take executive action and "save TikTok" following the implementation of a federal ban on the wildly popular video-sharing app.

"I’m asking companies not to let TikTok stay dark! I will issue an executive order on Monday to extend the period of time before the law’s prohibitions take effect, so that we can make a deal to protect our national security," Trump said in a statement on his social media platform, Truth Social.

The federal ban, which went into effect Sunday, forced TikTok to temporarily suspend its services. Trump's order, expected on Monday, aims to end the shutdown and open the door to negotiations.

In an earlier post on Truth Social on Sunday, the day before his inauguration, Trump had said: "SAVE TIKTOK!"

Trump, who will return to the White House on Monday to begin his non-consecutive second term, has already expressed sympathy for TikTok and urged the top court to postpone the decision to allow for negotiations.

TikTok CEO Shou Zi Chew is expected at Trump's inauguration.

The president-elect proposed a joint venture to keep TikTok operational in the US.

"I would like the United States to have a 50% ownership position in a joint venture. By doing this, we save TikTok, keep it in good hands, and allow it to stay up. Without U.S. approval, there is no TikTok. With our approval, it is worth hundreds of billions of dollars—maybe trillions."

"Americans deserve to see our exciting Inauguration on Monday, as well as other events and conversations," he added.

'Sorry, TikTok isn't available'

"Sorry, TikTok isn't available right now. A law banning TikTok has been enacted in the U.S. Unfortunately, that means you can't use TikTok for now," read a message from the app. "We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office. Please stay tuned!" it said.

Users are still allowed to log in to download their data.

The app is no longer available on the App Store or Google Play Store.

The company announced hours earlier that it would make its services "temporarily unavailable."

"We regret that a U.S. law banning TikTok will take effect on January 19 and force us to make our services temporarily unavailable," the popular video-sharing app said in a message to all users. “We’re working to restore our service in the U.S. as soon as possible, and we appreciate your support. Please stay tuned."

The US Supreme Court upheld a law on Friday to ban TikTok unless its Chinese-based parent company, ByteDance, divests from the app. The court ruled that the divest-or-ban ultimatum does not violate the company’s First Amendment rights in the US Constitution.

The White House said that the Chinese social media app should remain available in the US, but under American ownership to address national security concerns.

The bipartisan law, passed by Congress and signed by Biden in April, gave ByteDance 270 days to divest or face a ban.

* Yasin Gungor and Gizem Nisa Cebi contributed to this story from Istanbul