"I hit it pretty bad on the rim," said James, who iced his wrist in the locker room after the game. "It's like you hit your funny bone, but it's not funny at all."
He said it happened on one of his driving dunks that closed Cleveland's scoring with more than 2 minutes left.
"Didn't feel good at the time," said James, who added that he hurt the same wrist earlier this season.
He finished with 34 points and nine assists.