With two days remaining to the crucial match against Morocco in Group B of the 2018 World Cup, Dejagah is not completely fit for the competition.
Dejagah returned with a goal after about four months in late May in a friendly match against Turkey, where Team Melli lost 2-1.
He had suffered a knee injury in Nottingham Forest’s training in February.
The 31-year-old iconic midfielder had been a regular for Iran in their successful qualifying campaign and his absence in the key match against Morocco could be a big blow for Carlos Queiroz’s side.
Iran national football team will likely miss striker Mehdi Taremi in their first match.
Team Melli will meet the Atlas Lions on Friday in St Petersburg.
Iran, making their fifth appearance in the World Cup finals, meanwhile, face Spain in Kazan on 20 June before meeting Cristiano Ronaldo's Portugal in Saransk five days later.
Reporting by Masoud Hossein
MNA/TT