Team Melli lost to Slovenia 31-19 in its training camp in the European country.
Iran had already defeated Slovenian club RK Koper 33-32 in its camp.
Iran is preparing for the Asian Handball Championship, where it has been drawn in Group A along with Iraq and Japan.
Borut Macek’s team will kick off the event with a match against Iraq on January 19.
The 2018 Asian Men's Handball Championship will be the 18th edition of the championship held under the aegis of Asian Handball Federation.
The championship will be hosted at Suwon, South Korea from January 18 to 28, 2018.
It acts as the Asian qualifying tournament for the 2019 World Men's Handball Championship. For the first time, Australia, New Zealand and Bangladesh will participate.