The US Congress, as a legislative pillar of democracy, has a significant impact on American foreign policy. Nevertheless, the role of the US Congress is not limited to domestic politics rather they would usually shape the country’s foreign policy. Since the Islamic Revolution, the US Congress has adopted an aggressive approach towards Iran. The US legislative institution, as a domestic source of US foreign policy, has shaped US foreign policy toward Iran by imposing economic sanctions. The purpose of the research is to increase the Iranian officials’ understanding of US domestic politics. Therefore, the main question of the research is concerned with the impact of the US congress on American foreign policy towards Iran (2005-2017). In order to answer the main question, the authors would use neo-classical theory. In addition to systemic factors, neoclassic realism considers domestic factors to explain foreign policy. The findings of research suggest that the US congress has encouraged the US administrations to pursue an aggressive policy towards the Islamic Republic of Iran by imposing economic sanctions and persuading the US administrations to implement them

congress, US foreign policy, Islamic Republic of Iran, Neoclassic Realism, Foreign Policy