Ramin Mohtasham won the Golden Lens Award of the event while the Silver Lens Award went to Majid Doukhtechi.
The 50-year-old Mohtasham has already won many international awards including the Gold Medal for Creative Photography in Singapore.
The third top prize of the event, the Bronze Lens Award, also went to another Iranian photographer Hadi Dehqanpour.
The festival's jury panel granted the Young Talent and Knack Awards of the event to Iranian photographers Ali Ramezani and Mohsen Esmailzadeh.
Works of the 34th International Photography Festival Knokke-Heist winners will be displayed in the Cultural Knokke-Heist from March 25 to June 10, 2012.
Some 803 photographers from 37 different countries submitted more than 7,600 photos to the festival.
The festival consists of an outdoor exhibition and a number of indoor exhibitions.