By the triumph of moderates in the eleventh presidential election in Iran, the Iranian foreign policy in general and more specifically its nuclear diplomacy has changed dramatically so that the compromise strategy has overcome the confrontation orientation. The present paper is to explain the factors behinds this dramatic change by applying the decision making theory of James Rosenau. The findings of the paper illustrate that respectively the international system; individual and social factors are more determinant factors and have crucial roles in the Iran’s nuclear diplomacy since 2013.