After initially being booked by referee Anthony Taylor for the challenge on Carlos Alcaraz in the first half, it was upgraded following a VAR review.
The punishment is a four-game ban because the Brazil international was also sent off in the home win over Crystal Palace, again when VAR was used in the wake of a multi-player fracas.
Casemiro will miss the Emirates FA Cup quarter-final with Fulham this Sunday and next month's Premier League fixtures against Newcastle United, Brentford and Everton.
He will be available for Thursday's Europa League round-of-16 second leg away to Real Betis.