Hi Parastooh,
Something from the Lesser Whitethroat complex, but I'm not sure from these images which taxon, nor do I know what the most likely form would be in that area without checking the literature. It looks a bit different from an average curruca, though.
Regards,
Harry
According to Olsson
et al 2013, breeding
curruca occurs in an arc from Azerbaijan that includes Tehran, breeding
althaea is found in NW and SE Iran & breeding
minula in E Iran. However, in the non-breeding period,
halimodendri from Kazakhstan has wintered in SE Iran,
curruca is only a passage migrant,
blythi winters in C and S Iran, while
minula winters in SE Iran;
margelanica may have wintered occasionally in Iran in the 19th century (Khaleghizadeh
et al 2017
Birds of Iran). The odds are that the bird in question is
blythi, informally known as 'Taiga Whitethroat', but that's far from certain.