"He doesn't want to comment in public on his reasons for doing this," Jørgen Løvdal said.
The man, who wished to remain anonymous, was posted to Norway in 2009 and had been working at the Iranian embassy in Oslo, but defected in December, Løvdal said.
"Unfortunately we do not have any comment on this matter," a spokesman for the Iranian embassy in Oslo said when contacted by AFP.
The man would be the fourth Iranian diplomat to seek protection in a Nordic country in three years.
The ex-consul general of Iran's embassy in Oslo, Mohamed Reza Heydari, was granted asylum by Norway in February 2010 after resigning from his job.
A press attache at the Iranian embassy in Brussels, Farzad Farhangian who also defected to Norway in 2010, said in September that year he intended to join the opposition to President Mahmoud Ahmadinejad.
In the same month, a senior official at Iran's embassy in Helsinki, Hossein Alizadeh, sought asylum in Finland.
Tehran said personal rather than political motives were behind Heydari's and Farhangian's defections, while an Iranian MP accused the three diplomats of having mental problems.