If we insist on finding ourselves enemies we will never find peace! Need I remind you that Iraq, a country which we fought with for 8 years is now one of our closest friends? Need I remind you how many Palestinians, Lebanese, Sudanese, etc... volunteered to fight against us in the war with Iraq?!
I can assure you that U.S. did not kill as many Iranians as Saddam did, at least not directly!
If you wish not to be friendly towards a certain nation, that's alright, but it is not in our interest not to have any diplomatic relations with the U.S.; U.S. is a superpower whether some people like it or not, and enmity with this superpower has led our country which was well ahead of South Korea in terms of development (before the revolution) to lag behind and not be able to reach its full potential.
Diplomacy is not the about choices or likings, its about what you gain with whatever card you play and how you play it!