Let me remember you, me and my generation is in this deep shit (Islamic Republic) because your government has overthrown an elected democratic government in ~1952.
BTW I don't believe Hezbollah is a terrorist. Because it is not, It does not blow people in Marathon, It does not blow people in a restaurant in France. Yes, they do defend themselves against Israel. So as much as I hate , Hezbollah, they are not terrorist.
As for Hezbollah, while I don't think it is primarily a terrorist organization, and they did have the right to fight back against the Israeli army while it was occupying South Lebanon, Hezbollah bombed several non-Israeli civilian targets, often for purely religious reasons (or how else you would describe an attack on a Jewish community center in Argentina?).
Besides, Israel has been out of Lebanese soil for over 15 years, aside from a brief, ill-conceived war (that was nevertheless a response to an unprovoked Hezbollah raid on Israeli soil). During much of that time, Hezbollah did very much the opposite of defending Lebanon, and went out of it's way to provoke Israel to attack Lebanon, knowing that that would gain them legitimacy. This includes targeting Israeli tourists in Bulgaria (I have hard time seeing how this can ever be seen as defensive).
Nowadays, they calmed down on the antisemitic terror front, and it seems like they're mainly occupied with helping Assad massacre his own people (and pretty effective at that). It's hard for me to see anything positive about this group.
There is a whole Wikipedia page for you to browse.[1]
Has Iran directly committed a terrorist act again the United States? No, unless you stretch that definition a bunch.
Has it supported/funded terrorism against other Western countries? Absolutely.
[1]https://en.wikipedia.org/wiki/Iran_and_state-sponsored_terro...