Fatemi replaced Mohammad Mohammadi, who left the post two weeks ago to join Persepolis.
The center forward played for Iranian giants Esteghlal and Persepolis for five years.
Iran will participate in AFC U-23 Asian Cup to be held in Uzbekistan from June 1 to 19.
Host Uzbekistan, the 2018 champion, will have Iran, Qatar and newcomer Turkmenistan to contend with in Group A.