IIRC, Iran didn't get a corner kick, which implies that the ref didn't see anything at all. Since no corner kick, the ref "saw" that the Iranian player kicked the ball last and Zabaleta didn't touch it. If he didn't see Zabaleta's touch, then he should have given a penalty, but he didn't give this either, so this implies that he didn't even see that Zabaleta took the guy down.
This isn't a penalty, though. Zabaleta clearly goes for the ball and ends up touching it, but not kicking it as he wanted to, due to the opponent touching it first with his toe.