Reja insists Mauro Zarate and his men "were provoked" during the two brawls that marred their defeat at Bologna.
Gimenez was also red carded in that incident.
After the final whistle, former Birmingham City striker Zarate threw the ball at Matteo Rubin's head, allegedly spat in his face and then accidentally punched the referee's assistant when trying to strike one of the Bologna players in the ensuing melee.
"Gimenez provoked the brawl and he was the one to create all the problems," insisted Reja after the 3-1 defeat.
"He came off the bench and started pushing people, sparking the fight. We were provoked. Dias is a very fair player and it was our mistake to be sucked in by provocation.
"We also had some tension left over from losing the Coppa Italia derby midweek, while Bologna were playing the game of their lives."