Iran has funded numerous terrorist groups for years, ever since their revolution.
19/20 hijackers were Saudi (and more recently, so was one of the San Bernardino shooters, for all practical purposes). UBL was Saudi. Please point out to me terrorists with similar profiles who are/were Iranian.
Iran's funding of Hezbollah can be legitimately seen as defending their own interests. Just like we fund scores of militias all over the region.
Which part of assassinating Lebanese politicians, kidnapping and torturing soldiers, starting a war with a nuclear-armed state, and randomly firing unguided rockets into civilian towns can be legitimately seen as defending Iran's own interests?