Per Andrews, the 38-year-old is expected to miss approximately a month. The Bucks' last regular-season game is April 10. Milwaukee signed Gasol on March 3 following his buyout from the San Antonio Spurs.
Gasol previously missed time earlier this season after suffering a stress fracture in his left foot. That injury ultimately helped usher the end to his time in San Antonio.
Gasol is averaging 3.9 points and 4.6 rebounds per game this season but has only appeared in three games since joining the Bucks.
Milwaukee sits atop the Eastern Conference at an NBA-best 54-19 record.