The Argentine attacker's offence was caught on camera and he will now sit out the Giallorossi's Serie A matches against Fiorentina, Napoli and Chievo
The Argentina international, who only came on early in the second half of the game in Turin, was involved in an off-the-ball dispute with his Swiss opponent, which went unnoticed by the match officials but was captured by the television cameras.
On the evidence of the recorded footage, Lamela has now been suspended for his side's upcoming clashes with Fiorentina, Napoli and Chievo.
A statement from Lega di Serie A read: "The television images show that the Giallorossi player, in the centre of the field but at a considerable distance from the play, was close to the Juventus player and that he - presumably in response to a mocking gesture - spat on the left shoulder of the Bianconeri player, leaving a visible residue."
Lamela has been one of Roma's better players this season and his three-game ban is a blow for Luis Enrique's side, who are currently sixth in Serie A, five points behind third-placed Lazio.