US District Judge Susan Illston in San Francisco on Friday sided with a group of unions, non-profits and local governments, and blocked large-scale mass layoffs known as "reductions in force" for 14 days.
"As history demonstrates, the President may broadly restructure federal agencies only when authorised by Congress," Illston said.
The White House did not immediately respond to a request for comment.
The ruling is the broadest of its kind against the government overhaul led by Elon Musk, the world's richest person who is also CEO of electric vehicle maker Tesla .
Dozens of lawsuits have challenged DOGE's work on various grounds including violating privacy laws and exceeding its authority, with mixed results.
Trump directed government agencies in February to work with the Department of Government Efficiency to identify targets for mass layoffs as part of the administration's restructuring plans.
He urged agencies to eliminate duplicative roles, unnecessary management layers, and non-critical jobs, while automating routine tasks, closing regional field offices and reducing the use of outside contractors.
"The Trump administration's unlawful attempt to reorganise the federal government has thrown agencies into chaos, disrupting critical services provided across our nation," said a statement from the coalition of plaintiffs.
"Each of us represents communities deeply invested in the efficiency of the federal government – laying off federal employees and reorganising government functions haphazardly does not achieve that."
Illston scheduled a hearing for May 22 to consider a longer-lasting preliminary injunction.
