Sponsoring international terrorism used to be a real faux pas in the U.S. I guess those days are over.
The problem with Iran is their development of nuclear weapons, their ballistic missile program which now extends in range to cover the Europe, their support in weapons, money and training of various paramilitary groups such as the Houthis, Hezbollah, Hamas and Islamic Jihad, their oppression of their own citizens, hanging gays from cranes, various bombing and attack operations (US forces, Saudi facilities), attacks against oil tankers and calls to annihilate Israel. Not their support of Palestine.