Rivers is candid in giving his responses to questions, and evidently league officials didn't like how he answered when asked about Celtics center
"Listen, I thought the fouls on Kevin, first of all they were horrendous," Rivers said in the postgame news conference. "And secondly, I thought they had a huge effect on us."
He went on to say that there wasn't much he could do about it.
"That's just the way it goes," Rivers said. "There's nothing I can do about it now. I thought if it could've gone either way on three of those [fouls], they all went against Kevin. I think that's tough."
After hearing about the fine on Thursday, Rivers downplayed his criticism of the referees.
"I didn't think I said much and that could be a problem," Rivers said. "Because all I basically said was, Kevin getting into foul trouble had a huge impact on the game. That's not criticizing officials. So I've just got to make sure I focus on our stuff."
Wire service and Internet reports contributed to this story.