The court said games can be staged on Fridays, but not Mondays.
The Royal Spanish Football Federation (RFEF) said in July that La Liga games cannot be played on Fridays and Mondays without its approval.
Fixtures had already been scheduled and Athletic-Barcelona was moved to the Saturday, but now returns to Friday.
Two games on Monday, 19 August must now be moved.
The RFEF said supporters only wanted games on weekends and that Monday fixtures in particular made it “very difficult for fans to enjoy games”.
La Liga feared that would threaten its 2bn euro broadcast deals.
The case went to court after the two sides failed to reach a compromise at a meeting organised last month by the government’s National Sports Council (CSD).
Judge Andres Sanchez Magro announced the provisional ruling at a commercial court in Madrid in a 32-page document on Friday.
La Liga says it will appeal against the decision and says it contains “clear contradictions and passes judgment over issues it was not required to without offering sound judicial motives, arguments or reasoning”.
It also said it would contact operators and international broadcasters and do all it can to “ensure the negative effects are as limited as possible”.
La Liga has now called an Extraordinary General Assembly with all clubs from the top two tiers of Spanish football on Monday.
Meanwhile, RFEF president Luis Rubiales called it “an historic day” and added: “My commitment to the fans to banish Mondays from our football has been fulfilled.”