La Russa commented on the broadcast that home plate umpire Jerry Meals had "two different strike zones."
Tuesday before Game 3, La Russa said he had "no disagreement at all" about being fined the undisclosed amount.
"I'm embarrassed that I crossed the line," La Russa said. "I know what the line is. I got upset and I crossed the line. If I get a chance, I will apologize to Jerry. Like I said, I've never had any problems with him. He's a pro. He has my utmost respect. We were competing, and I got upset and crossed the line."
The Cardinals went on to win Game 2, 5-4, to even the series at a game apiece.
La Russa also said Tuesday that outfielder Matt Holliday will be available to pinch-hit for Game 3.
Holliday was not in the lineup for the first two games because of a tendon injury in his right hand, and has still not improved to the point where he can start. However, La Russa did say his understanding was that Holliday's condition has improved.