Judge Carl Nichols of the US District Court for the District of Columbia issued a temporary ban on Sunday evening at the request of TikTok, reports BBC.
The ruling followed an emergency hearing Sunday morning in which lawyers for TikTok argued that the administration's app-store ban would infringe on First Amendment rights and do irreparable harm to the business.
The app had faced being blocked from Apple's App Store and Android's Google Play marketplace from 23:59 Eastern time.
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Existing US-based users would have been able to continue using it. But they would not have been able to re-download it if they deleted it from their phones, nor have been offered software updates.
Earlier this year, President Trump declared that TikTok, owned by Chinese company ByteDance, was a threat to national security and that it must either sell its US operations to American companies or be barred from the country, reports AP.
TikTok is still scrambling to firm up a deal tentatively struck a week ago in which it would partner with Oracle, a huge database-software company, and Walmart in an effort to win the blessing of both the Chinese and American governments.
In the meantime, it is fighting to keep the app available in the US.
TikTok said in a statement that it was pleased with the court ruling and continues to work to turn its deal proposal into an actual agreement.
The Commerce Department, which is responsible for the specific orders banning TikTok, said it will comply with the judge's order but intends to vigorously defend the administration's efforts against the app.
Judge Nichols did not explain his reasoning publicly, and instead filed his judicial opinion under seal.
Initially both the US government's brief in the case and the entire Sunday morning hearing were also due to be sealed from the public, although the court later relented.