A federal judge ordered the Trump administration on Thursday night to unfreeze foreign aid spending President Trump halted during his first week in office, the latest of several legal roadblocks to Mr. Trump’s aggressive first-month agenda.

The ruling by Judge Amir H. Ali of the Federal District Court in Washington found that Mr. Trump’s executive order imposing a blanket freeze on U.S. foreign aid spending was based on dubious logic. He said it was also probably causing irreparable harm to aid groups, which face devastating financial shortfalls and, in some cases, shutdown.

In response, Judge Ali, a Biden appointee, issued a temporary injunction saying that the Trump administration could not freeze foreign aid spending that predates Mr. Trump’s inauguration, nor could it fire or suspend workers associated with those spending projects.

The ruling reverses a decision that had thrown into turmoil programs that provide shelter for millions of people and fight hunger and illness around the globe. Other court decisions have also blocked the administration from carrying out its plan to virtually dismantle the U.S. Agency for International Development, the main government organization that provides humanitarian aid, and put its employees on administrative leave.

In his 15-page ruling, Judge Ali said that the plaintiffs — a coalition of aid groups, businesses, and health and media nonprofits — had “made a strong preliminary showing of irreparable harm.”

He cited the example of one nonprofit that protects refugees and asylum seekers. It reported having to lay off 535 staff members after losing federal grants, shutter program offices and defer payments to its vendors.