SAN FRANCISCO (Reuters) - A U.S. court has handed down a preliminary decision to halt Vivendi SA's $8.2 billion (5.08 billion pounds) deal to sell most of its stake in Activision Blizzard Inc back to the U.S. company, the games publisher said on Wednesday.

Last week, an Activision shareholder had filed a lawsuit against both parties, seeking an injunction to the deal. The company said the Delaware Chancery court had issued a preliminary injunction on the deal.

"Activision Blizzard remains committed to the transaction and is exploring the steps it will take to complete the transaction as expeditiously as possible," the publisher said in a statement.

(Reporting by Malathi Nayak; Editing by Bernard Orr)