The Blues has hired Zob Ahan striker Morteza Tabrizi and German midfielder Markus Martin Neumayr on Tuesday.
Tabrizi and Neumayr have joined Esteghlal on a two-year contract for an undisclosed fees.
Tabrizi, 27, started his football in 2010 in Pas Hamedan and joined Zob Ahan after three years.
He has scored 39 goals for the Isfahan-based team in 138 matches.
Neumayr, 32, began his football career playing for local clubs before moving to Eintracht Frankfurt in 2003, however, within a few months, he was picked up by Manchester United.
During his spell with Manchester United, he played on the right side of midfield, although on some occasions he would play in the middle of the park.
Neumayr has also played at MSV Duisburg, Wacker Burghausen, Bellinzona, FC Luzern and Kasımpasa.
The Iranian team must strengthen itself since it will face Qatar’s Al Sadd in the AFC Champions League’s quarter-final in late August.