The play occurred in the first quarter, with Green Bay facing a third-and-two situation from its own 21-yard line.
Packers quarterback Brett Favre threw deep for Driver, who was running a post pattern. The veteran wideout got a hand on the ball, but couldn't pull it in, as McCree delivered a hit to Driver's head which knocked the receiver's helmet off.
McCree drew a 15-yard unnecessary roughness penalty for launching himself into what the league termed a "defenseless" receiver. The penalty moved the ball to the 36-yard line, and extended the Green Bay drive, which culminated in a field goal. A shaken Driver left the game for a short time, but returned four plays later.
After the game, Driver referred to the play as "a cheap shot." The wide receiver has suffered no lingering effects from the play. League officials reviewed the incident this week and felt that it warranted a fine.
It is not known if McCree, a seventh-year veteran, will appeal the fine. McCree, 30, has a base salary of $650,000.
McCree, who joined the Chargers as an unrestricted free agent in 2006 and immediately added stability to the secondary, has 19 tackles, one interceptions and two passes defensed in three games this season.
Senior writer Len Pasquarelli covers the NFL for ESPN.com