Applying a conceptual model derived from the theory of hegemonic stability, this paper is intended to answer the question of how US strategy in the era of Donald Trump in the Indo-Pacific region affects Iran's national security. The US goal of its attendance in the Indo-Pacific region contains expanding its power and developing its hegemony over the region. Given the fact that this region is one of the most challenging one for the maintaining of hegemony, the United States pursues its attempts to increase the weight of India in the Indo-Pacific region to constrain China. This is because China is considered as a close threat to America, but India seems to be a distant threat. Therefore, regarding the fact that India, as a medium power in the future, is not a potential challenge US interests in the region, America is trying to control China by strengthening India’s power, an event that directly and indirectly affects the security of the Islamic Republic. Through a descriptive-analytical method, the researchers are to test the hypothesis that the US policy in the Indo-Pacific region increases tensions in Iran's close neighboring countries result in reducing US attention to the Persian Gulf, India's withdrawal from non-aligned treaty and possibly adding to the tensions in Iran's relationship with two countries of China and Pakistan. However, Washington's interest in resorting to Delhi’s power against Chinese can potentially facilitate the expansion of India's relationship with Iran.