One reason behind the rift between the USA and Iran is the latter's soft corner towards Hamas. Article#9 of the Charter of Hamas (an Islamic organization ruling Gaza since 2007 declared terrorist by US, UK and Israel while not considered as terrorist by Russia, China, Turkey and Iran) pointing out the Jewish state of Israel claims that, “The state of truth (Palestine) has disappeared and was replaced by the state of evil (Israel).”
The section further pledges for; “Discarding the evil, crushing it and defeating it, so that truth may prevail, homelands revert [to their owners], calls for prayer be heard from their mosques, announcing the re-institution of the Muslim state.”
Sentiments similar to that were reflected in various statements of Iranian leadership;
That’s not all; Iran’s views about American backed Israelian state in Asia have remained harsh for years, more particularly in Ahmadinejad's past regimes and even today. So, with these passions Iranian ties with the US can’t grow strong, as Israel, the most adored Asian state by America is being threatened. Israel feels insecure in the region due to the objectives of Hamas especially when they are backed up by the Iranian military weapon supplies like Fajr-5, M-75, and M-302 rockets, as well as drones to Hamas. With such situation real, US can't be polite with Iran from Israeli point of view.