Mehdizadeh defeated Vladimir Kalashnikov from Russia 8-0 in the Male Kumite -60 kg event in the bronze medal match and finished in third place.
Ahmadi also won the bronze medal in the -67kg after beating Thomas Jordan from England 6-0.
Iran took part in the competition in Germany with eight men and women karate practitioners.
The competition has reportedly brought a total of 1,384 male and female karate practitioners from 87 countries together.