The 52-year-old coach will replace Kurban Berdyev, who parted ways with Tractor last week after about five months.
Jémez started his coaching career in Córdoba and has also coached La Liga teams Deportivo La Coruña and Rayo Vallecano.
Turkish football coach Ertugrul Saglam was also a nominee to take charge of the Tabriz-based football team.
Tractor sits seventh in the Iran Professional League (IPL), nine points behind leader Persepolis.