The Mavs said Barea is weighing his options for surgery.
Barea, 34, a longtime Dallas fan favorite who played a key role on the 2011 championship team, has been the leader of one of the NBA's most effective bench units this season. He is averaging 10.9 points and 5.6 assists in 19.8 minutes per game.
The injury ends Barea's season and puts in doubt his availability for the start of next season. Barea, a former undrafted free agent in his 13th NBA season, is in the final year of his contract but has said he plans to play at least two more seasons.
Barea, who had 16 points and seven assists in the win over the Timberwolves, was injured after cutting for a layup with 6 minutes, 28 seconds remaining in the game. He grabbed his right Achilles while on the floor. Several teammates, including Dirk Nowitzki, offered words of encouragement for Barea before he was helped to the locker room.