During the first half of Inter's 2-1 defeat at Chievo, Eto'o got into a row with the defender, claiming he had been hit on the face by a trailing arm.
The Cameroon striker then reacted a few moments later by head-butting Cesar in the chest, unseen by the officials.
"Eto'o is a great player, but I think this sort of behaviour simply should not happen," said the defender.
"He head-butted me and did not even apologise. I can't be too unhappy, though, as the important thing is that Chievo got the three points.
"It was a very important victory for us and our campaign, so we must continue along this path."