Are you aware that Iran approved of US invasion of Iraq in the Gulf War? It even allowed the use of it's air space.
Are you aware that Iran was the only country excluded from the Madrid peace talks of 1991 between Israel and Palestine? To counter this exclusion, Iran strengthened it's ties with Hamas and Hizbollah.
Iran is not some insane theocracy seeking of everyone's destruction. The regime is bad for the people, but self-interested just as any other, and benefits very little from full exclusion.