The Welshman was adjudged to have gone to ground too easily under a challenge from Walter Gargano and received his third booking of the season in the Europa League
The in-form wideman opened the scoring for Spurs in the sixth minutes with a headed finish but earned a yellow card for simulation moments later after clashing with Walter Gargano in the visitors' box.
Having also been booked in his side's meetings with Panathanaikos and Maribor earlier this season, the Welshman is now set to serve a one-match suspension.
Bale will now miss out on a return to the San Siro, where he famously made his name with a quick-fire hat-trick against the then-European champions back in 2010.
The 23-year-old's opener against the Italians was his 25th goal in 40 appearances so far this season.