The fine stems from a play with 8:05 left in the third quarter of Thursday's game, when Chalmers was attempting to fight through a screen and raised his forearm into Griffin's neck.
Chalmers was called for a common foul during the game, but the league upgraded the infraction on Friday to a flagrant foul 1.
Chalmers appeared to complain to referees immediately after the play that the shot on Griffin wasn't intentional. Griffin grabbed his neck and shook off the blow, but did not attempt to retaliate.
Griffin finished with 27 points and 14 rebounds in the 102-97 loss to the Heat.