The versatile forward featured from the start in the second leg of the last 16 cup match at the Reyno de Navarra, but was forced to leave the pitch after 68 minutes of play due to the knock.
Pedro will be out of action for the next 10 days, which means that he will miss Barca's Liga matches against Betis and Malaga, and next week's Clasico at the Santiago Bernabeu.
The 24-year-old has so far made 25 appearances in all competitions this season, scoring six goals.
Starting in November and continuing through January, Goal.com is publishing exclusive extracts from Graham Hunter's highly-anticipated new book, 'Barca: The Making of the Greatest Team in the World'. On Friday, the latest extract will take a closer look at the exciting emergence of Fifa Ballon d'Or winner Lionel Messi at Camp Nou: Don't miss it!