Ambient seismic‐noise correlation is a powerful tool for extracting the seismic core phases that propagate through the interior of the Earth. In this study, we present and refine the root‐mean‐square‐stacking method to extract stable core phases (e.g., PcP, ScS, PcS/ScP, and PKiKP) from within the Central Alborz region, Iran, using empirical Green’s functions. Our studies on the extracted core phases using empirical Green’s functions indicated that the ambient seismic noise method is independent from global seismicity (M≥5.5). We also show that, by dividing ambient seismic records into shorter (i.e., 2700 s) and overlapping (70%) time windows, before the cross‐correlation procedure, we can improve the quality and stability of the empirical Green’s functions generated. Consequently, 73 days (equivalent to 22% of the total time period for the dataset) of nonconsecutive ambient seismic‐noise time windows have been used to retrieve core‐phase empirical Green’s functions in a 5–10 s period band.