Beasley landed awkwardly after making a layup with 8:10 remaining until halftime, immediately grabbing his left hip after falling on his side to the court. He got up and took a few steps, face writhing in pain, before going down again near the Timberwolves' bench and needing assistance to reach the locker room.
Beasley was quickly diagnosed with a bruise and was getting X-rays, which were negative, the Timberwolves said.
It was Beasley's first game back in Miami after spending two seasons with the Heat, who traded him in July for second-round picks in 2011 and 2014. Beasley had been Minnesota's leading scorer through the season's first three games, averaging 14.7 points.
"It's unfortunate," Minnesota coach Kurt Rambis said. "Right now we don't have the luxury of having someone like him, a starter, being out of the ballgame."
Beasley's status for Wednesday's game at Orlando is unclear, Rambis said.
By league rules, his night officially ended when he was unable to shoot the resultant free throw, which was eventually taken by Kosta Koufos. Given the amount of pain he appeared to be in while being aided to the locker room, it didn't appear likely that Beasley would be returning anyway.
He finished with 11 points on 4 of 9 shooting in 10 minutes, including a one-handed slam off an offensive rebound midway through the opening quarter.
Information from The Associated Press was used in this report.