I suggest you search for and consider the available Erasmus+ programs for doctoral scholarships for students from Iran. Erasmus+ is the European Union programme for education, that funds academic mobility and cooperation projects throughout the world. Under the previous programme Erasmus Mundus, fellowships were also awarded for doctoral programmes (last award 2017).
Furthermore , you have not clearly explained the area of your research.
I am a civil engineer and my research field is the railway infrastructure (tracks, substructure, etc.).
Best regards from Belgrade!
Zdenka Popović, PhD Civil Eng.
Full professor
University of Belgrade,
Faculty of Civil Engineering, Department of roads, airports and railways