The Clippers said Gallinari will be re-evaluated in January.
The 29-year-old missed 13 games between Nov. 7 and Dec. 3 nursing a strained left glute. He returned to the floor Dec. 6, but he hit the shelf again Dec. 11 and has missed the Clippers' last five games.
Gallinari, who's in the first year of a three-year, $64.7 million deal, is averaging 13.4 points and 4.4 rebounds per game on 34.5 percent shooting from the field and 25.8 percent shooting from three.
The setback is another disappointment for the Clippers, who have been plagued by injuries to key contributors all season long.
Beyond Gallinari, L.A. has been forced to operate without point guard Patrick Beverley (season-ending knee surgery) and power forward Blake Griffin—who is expected to be out until late January with a sprained left MCL.
The Clippers, who are 11-18 overall, enter Wednesday night's game against the Phoenix Suns on a three-game losing streak.