As I said, Suarez is a centre forward and Ivanovic a centre half, there would have been provocation and niggle all game. Goes with the territory. Ivanovic rakes his studs down Saurez's achilles and nobody bats an eyelid, leaves his elbow in when winning a header, not a big deal.
It's just the nature of the Suarez retaliation that people have trouble getting their heads around.