De Rossi banned for three matches
De Rossi was dismissed by referee Gianluca Rocchi in the closing seconds of the first half after he slapped Lazio's Stefano Mauri.
The Serie A frowned on the Italy international's actions and slapped him with a suspension.
The 29-year-old was already dropped from the Italy squad by national team coach Cesare Prandelli following his red card, and he will now have to watch Roma's next three league games from the stands too.
His suspension means that De Rossi misses Serie A matches versus Torino, Pescara and Siena.
Roma coach Zdenek Zeman will also be without the likes of Nicolas Burdisso and Panagiotis Tachtsidis against Torino as the duo were handed one-match bans after they both received their fourth yellow card of the season against Lazio.