French midfielder Robert Pires insulted the referee after Villarreal lost 2-1 away to Xerez on Sunday, the referee involved, Antonio Rubinos Perez, said in his report posted on the La Liga website.
"Once the game was finished and when I was still on the pitch, I cautioned Villarreal player Joseba Llorente for his strong protests," Rubinos Perez said.
"As a result of this incident, Villarreal player Robert Pires said to me: 'You are a son of a whore.'"
Promoted Xerez won their first ever game in the Spanish top flight with a controversial goal 11 minutes from time.
Villarreal goalkeeper Diego Lopez's clearance out of the area struck Xerez's Carlos Calvo on the arm before falling to team mate Antonito who lobbed the ball back into the empty net.
The result moved Xerez off the foot of the standings up to 18th while Villarreal slumped to 20th. Ernesto Valverde's side have yet to win a game this season.