The club added that Cellino was “attempting to downplay the excessive media coverage by protecting [Balotelli]”.
Balotelli experienced racism at the beginning of his career in Italy, when he rose to prominence with Inter Milan, and he was also the target of racist chants earlier this month during a match at Hellas Verona.
The game in Verona was suspended for several minutes and Balotelli threatened to leave the field after angrily kicking a ball into the stands.
Derogatory chants have also been aimed at Romelu Lukaku, Franck Kessie, Dalbert Henrique, Miralem Pjanic, Ronaldo Vieira and Kalidou Koulibaly in Serie A this season.
All the players targeted – except for Pjanic, who is Bosnian – are black.