Bonacic replaced Miodrag Radulovic who didn’t return to Isfahan after leaving the team in March due to the coronavirus outbreak.
Bonacic had worked in the Isfahan-based football club in 2013-14 season.
The 65-year-old coach has worked in many Iranian teams including Foolad, Sepahan, Gostaresh, Esteghlal and Mes Kerman.
Zob Ahan sits 11th in the Iran Professional League, six points above relegation zone.