Napster fears a court ruling could force it to shut down its online music swapping service.
A US appeals court says Napster must stop trading in copyrighted material.
The Recording Industry Association of America hailed the ruling as a victory.
Napster must prevent users from gaining access to copyrighted content through its lists of songs archived by the service's users.
In a 58-page opinion, a three-judge panel told a lower court judge to rewrite her injunction to focus more narrowly on the copyrighted material.
The panel also directed the Redwood City-based company to remove links to users trading copyrighted songs stored as MP3 files.
Hilary Rosen, president and chief executive of the Recording Industry Association of America, said: "This is a clear victory. The court of appeals found that the injunction is not only warranted, but required. And it ruled in our favor on every legal issue presented."
Napster can stay in business until US District Judge Marilyn Hall Patel retools her injunction, which the appellate court called overly broad.