"The principled policy of the Islamic Republic of Iran is [based on] rejecting violence, extremism and terrorism and fighting this anti-human phenomenon,” Foreign Ministry spokeswoman Marzieh Afkham said.
She also sympathized with the bereaved families of the victims as well as the Nigerian government and nation.
At least 26 people lost their lives and 28 others were injured following the bomb explosion inside the mosque in Maiduguri.
The assailant, who pretended to be a worshiper, detonated his explosives inside the mosque next to the Monday Market of Maiduguri when the afternoon prayers began at about 3:30 pm local time (1430 GMT) on Saturday.
No group or individual has so far claimed responsibility for the deadly blast, but Nigerian officials often blame such attacks on Boko Haram Takfiri terrorists, mostly active in the northeast of Africa’s most populous country.
The bombing followed Boko Haram rocket attacks on a residential area in Maiduguri which killed 13 people. The rocket-propelled grenade attacks in the capital and the largest city of the restive Borno State also destroyed a number of houses.
The two attacks came a day after the inauguration of President Muhammadu Buhari, who swore to tackle the "enormous challenges” of corruption and the insurgency from the Boko Haram Takfiri group.