The 27-year-old player is the team’s first transfer in the January window, sdna.gr reported.
Haji Safi signed a two year contract with Greek Super League side Panionios in June 2017 and teamed up with his fellow Masoud Shojaei.
He will reunite with his countryman Karim Ansarifard in Olympiakos.
Haji Safi has represented Iran at the 2011 AFC Asian Cup, the 2014 FIFA World Cup and the 2015 AFC Asian Cup.