Bernal was sent off in the 54th minute, moments after Betis had scored to level the scoreline at 2-2 on Saturday. The disciplinary report published on Wednesday by the RFEF stated that Bernal grabbed Barcelona forward Lamine Yamal by the neck before headbutting him twice.
The 23-year-old was deemed to have assaulted Lamine, with the ball not in play. The disciplinary code states that bans range from four to 12 games for such behaviour, with the minimum imposed on Bernal.
Lamine was booked for pushing Bernal before the red-card incident. Barcelona went on to score three goals after Bernal's sending off, with Lamine assisting Gabriel Jesus for the Catalan club's third goal of the game.
Betis sporting director Manu Fajardo was also sanctioned with a two-game suspension and a fine for conduct contrary to good sporting order.
The Uruguayan midfielder will miss Betis' LaLiga games against Celta Vigo, Malaga, Elche and the derby clash with Sevilla on November 22nd.
Betis are fourth in the LaLiga standings on 19 points.