Iranian football club Tractor appointed Soldo as coach in mid-November but the Croat failed to turn around the team's fortunes, with the team dropping into the relegation zone for the first time in recent years.
Tractor sits 13th in the 16-team table in Iran Professional League.
Tractor will have to host Sepahan on Monday in Tabriz on Matchweek 20 of the IPL season.