Up the Tigers
As there is no valid melee target you are effectively "choosing" not to play the ability and so this from page 1 on the FAQ applies
Can I choose to not perform specific parts of an action?
You can choose not perform any or all parts of an action if you want, such that you could discard a card and not use it at all. You cannot change the order of the abilities in the action, though, and you do have to perform any part of the action that would have a negative effect on yourself or your allies.