The 25-year-old Wolfsburg fan favourite bemoaned his team's 1-2 loss to Hoffenheim on Saturday, but nevertheless is excited about his new challenges with Team Melli.
"I rather would have gone after a home victory. Neverthelss, I am happy it finally worked out.
"I am looking forward to this experience and will try to make the best out of it", the former Hertha Berlin winger added.
Tehran-born Dejagah has played for several German youth teams, however, became eligible to play for Iran's senior national team after a change in FIFA regulations in 2009.
The 2009 Bundesliga and European U21 champion had rejected several invitation by Iran's Football Federation, most recently for the 2011 Asian Cup, before finally changing his mind later in the same year.
Dejagah had been invited for the previous three World Cup qualifiers in late 2011, however, had to reject due to injury and passport issues, which meanwhile have been solved.