Rupture directivity effects that cause spatial variations in ground motion amplitude around faults, is a parameter of seismic source that plays a significant role in generation of ground motions (and damage of structures, if the earthquake is large enough). Damavand-Mosha earthquake of 2020/05/07, Mw 5.0, occurred on the Mosha fault. To investigate rupture directivity of the mainshock we analyzed accelerograms recorded by the BHRC network. Larger amplitudes accelerations recorded in the stations west of the earthquake epicenter suggest mostly westward unilateral rupture propagation along the Mosha fault. This can be important in terms of seismic hazard for the Tehran megacity