The striker, who scored the equaliser for his country in their 1-1 draw with Portugal at the World Cup, will play as a forward for Nottingham Forest.
Karim Ansarifard has been without a club since being released by Olympiakos - the Greek club owned by Forest majority shareholder Evangelos Marinakis - in August.
He scored 17 goals in 26 league appearances for Olympiakos last season and featured against Burnley in the Europa League earlier this term.
Both Forest and the Greek giants are owned by Vangelis Marinakis and the 28-year-old is reported to have signed an 18-month deal with the Midlands club.
Forest are seventh in the Championship table, two points outside the play-off places, having won one of their last three games.
Aitor Karanka's men are in action at home to league leaders Sheffield United on Saturday.
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