Harrison and two other NFL defensive players were singled out by the league for discipline this week after a rash of concussions and neck injuries in Sunday's games.
Harrison, a three-time pro bowler, was cited for a helmet-on-helmet hit on Cleveland Browns receiver Mohamed Massaquoi.
"How can I continue to play this game the way that I've been taught to play this game since I was 10 years old?" Harrison told Sirius XM Radio. "And now you're telling me that everything that they've taught me from that time on, for the last 20-plus years, is not the way you're supposed to play the game anymore. If that's the case I can't play by those rules. You're handicapping me."
Steelers head Coach Mike Tomlin, however, told the Pittsburgh Post-Gazette he expected Harrison to return to practice after being given the day off Wednesday.