Fiddler's Green (Red)

Fiddler’s Green triggers when it is put into your graveyard from anywhere (e.g. put into the graveyard from the combat chain, discarded from your hand, destroyed from the top of the deck, put into the graveyard). You will gain the appropriate amount of specified by its effect when the triggered effect resolves.

Unless a rule or effect allows you to do so, you cannot declare defending cards against attacks where the attack-target is an ally you control.