The United States Court of Appeals for the Federal Circuit in Washington said it was pausing the lower court's ruling to consider the government's appeal, and ordered the plaintiffs in the cases to respond by June 5 and the administration by June 9.
Wednesday's surprise ruling by the US Court of International Trade had threatened to kill or at least delay the imposition of Trump's "Liberation Day" tariffs on most US trading partners.
There were also import levies on goods from Canada, Mexico and China related to his accusation that the three countries were facilitating the flow of fentanyl into the US
Senior Trump administration officials had said they were undeterred by the trade court's ruling, saying they expected either to prevail on appeal or employ other presidential powers to ensure they go into effect.
The White House also said the ruling had not interfered with any negotiations with top trading partners that are scheduled in the days ahead.
US trading partners "are coming to us in good faith and trying to complete the deals before the 90-day pause ends," Treasury Secretary Scott Bessent said in a Fox News interview.
"So we've seen no change in their attitude in the past 48 hours. In fact I have a very large Japanese delegation coming to my office first thing tomorrow morning."
A fourth round of talks with Japan is set for Friday in Washington, and a trade negotiating team from India is headed to the US next week for talks.
Many US trading partners offered careful responses.
The British government said the trade court's ruling was a domestic matter for the US administration and noted it was "only the first stage of legal proceedings."
Both Germany and the European Commission said they could not comment on Thursday's decision.
Canadian Prime Minister Mark Carney welcomed the trade court's finding, saying it was "consistent with Canada's longstanding position" that Trump's tariffs were unlawful.
Financial markets, which have whipsawed wildly in response to every twist and turn in Trump's chaotic trade war, reacted with cautious optimism to the trade court ruling, though gains in stocks were largely limited by expectations that the court's ruling faced a potentially lengthy appeals process.
Indeed, analysts said broad uncertainty remained regarding the future of Trump's tariffs, which have cost companies more than $US34 billion in lost sales and higher costs, according to a Reuters analysis.
Emblematic of that uncertainty, a separate federal court earlier on Thursday had also found Trump overstepped his authority in using the International Emergency Economic Powers Act for what he called "reciprocal" tariffs of at least 10 per cent on goods from most US trading partners and for the separate 25 per cent levies on goods from Canada, Mexico and China related to fentanyl.
That ruling was much narrower, however, and the relief order stopping the tariffs only applied to the toy company that brought the case.
