Rondo was on the bench after suffering a right thumb fracture in Game 2. The Bulls are up 2-1 in the series; Game 4 is Sunday night, and Rondo said he will be out a "couple weeks."
NBA vice president of basketball operations Kiki VanDeWeghe announced the fine.
Rondo said after the game Friday that he was not trying to trip the Celtics player.
"When you tear an ACL, your legs get stiff on you every once in a while," Rondo said. "I stretched my leg out. I also do that throughout the game. I guess he was so deep into our bench, it looked maybe whatever may have happened."
Celtics swingman Gerald Green said Saturday that he might believe Rondo's stretching excuse.
"He may have had to stretch his leg out. I don't know," Green said. "I ain't no snitch, so I don't know. That's not something I grew up being a part of. Where I'm from, they know snitches get stitches. So I don't know."