I hate to call here but I hate to fold, too.
He might have slowplayed a set on the flop and now pushes, fearing flush and straightdraws. He also might have only AK, KK, JJ, KQ, QT, KT etc. with one diamond. Or even hit his fd an wants to trap you with his push.

I think I will close my eyes an hit the "Call"-Button, but I don't know if it's the right play.