Spokesmen for the IMN said on Friday clashes that erupted between police forces and protesters in the capital, Abuja, this week left at least 20 people dead, according to Press TV.
One spokesman said the death toll may be as high as 25.
IMN members regularly take to the streets of the Nigerian capital to call for the release of Sheikh Zakzaky, their leader, who has been in detention since 2015.
Nigerian forces have used live ammunition against the protesters, according to media reports.
Sheikh Zakzaky, who is in his mid-60s, lost his left eyesight in a 2015 raid by security forces that left more than 300 of his followers and three of his sons dead. His wife also sustained serious wounds.
The Tehran Friday prayers interim Leader Ayatollah Khatami blamed Saudi Arabia and Israel today for the crackdown on the protesters by the Nigerian security forces and illegal detention of Sheikh Zakzaky.
MNA/PR