TikTok has won a last-minute reprieve as a US federal judge halted enforcement of a politically charged ban ordered by the Trump administration on downloads of the popular video app, hours before it was set to take effect.

District Judge Carl Nichols issued a temporary injunction at the request of TikTok, which the White House has called a national security threat stemming from its Chinese parent firm's links to the Beijing government.

The opinion was sealed, so no reason for the decision was released in a brief order by the court in Washington. The judge may unseal portions of the order after consulting with lawyers from both sides.

The Trump administration order had sought to ban new downloads of the app from midnight (5am Irish time) but would allow use of TikTok until 12 November, when all usage would be blocked. The judge denied TikTok's request to suspend the 12 November ban.

The decision represents a temporary win for TikTok, which has 100 million US users. But the court has yet to consider the merits of the legal arguments on whether the social platform should remain available to Americans.

TikTok has argued that even a temporary ban would be devastating and cause the company irreparable harm by stunting its growth and hurting its commercial reputation.

"We're pleased that the court agreed with our legal arguments and issued an injunction," TikTok said in a statement.

"We will continue defending our rights for the benefit of our community and employees."

For the injunction, Judge Nichols heard arguments on the free-speech and national security implications of the Trump ban on the Chinese-owned app in a rare Sunday telephone hearing.

TikTok lawyer John Hall said a ban would be "punitive" and close off a public forum used by tens of millions of Americans.

In a written brief filed ahead of the hearing, TikTok lawyers said the ban was "arbitrary and capricious" and "would undermine data security" by blocking updates and fixes to the app.

The company also said the ban was unnecessary because negotiations were already under way to restructure the ownership of TikTok to address national security issues raised by the administration.

Government lawyers argued the president has a right to take national security actions, and said the ban was needed because of TikTok's links to the Chinese government through its parent firm ByteDance.

A government brief called ByteDance "a mouthpiece" for the Chinese Communist Party and said it was "committed to promoting the CCP's agenda and messaging".

After the judge's order, the Commerce Department said in a statement it would comply with the injunction but "intends to vigorously defend the (executive order)... from legal challenges".

University of Richmond law school professor Carl Tobias called yesterday's order "a pragmatic splitting of the baby for the short term, to give a little time for them to resolve the disputes and come to a resolution".

Mr Tobias said an appeal is possible but that the legal teams may choose to "try to work out a resolution to the broader legal clash" with the judge.