I think the individuals who are currently running Iran believe enmity toward the United States to be an inextricable part of the Islamic Republic's identity and ideological narrative.
This doesn't mean that we shun dialogue with Iran, but we should have realistic expectations of what it will achieve. Our conflicts with Iran are not due to simple misunderstandings, but real, serious differences about the way the world ought to be. For me the utility of negotiations is not necessarily to resolve our differences with Iran, but to contain our differences and to mitigate the prospects of escalation and conflict.
I think the mathematics of a military strike make it highly inadvisable. According to best estimates it could delay Iran's nuclear progress by 2-3 years, but it would likely entrench Tehran's most radical elements for years, if not decades, to come. I think Iran's hardliners--including Khamenei--would welcome a military strike; they would use it as a pretext to crush dissent and repair the country's internal political divisions.As one Iranian democracy activist once told me, there should be "less focus on the gun, and more focus on the bandit trying to obtain the gun." Bombing Iran will strengthen the bandit and only increase his desire to get the gun.