Islamic Interpretation of Dreams (Ibn-i Sirin):

(Striking) Slapping someone on his cheek in a dream means cautioning him or warning him about his heedlessness.

If a woman gently slaps her own cheeks in a dream, it means glad tiding of a son she will conceive at an advanced age, or after havinglost hope in conceivingchildren. However, slappingsomeone’s face in a dream also could mean injustice, an illness, or cold.

(Also see Slapping on the cheek)