Shahin Najafi released a song last week criticizing Iranian society and politics, The Daily Trust reported Wednesday.
Najafi, who has lived in Germany since 2005, said in an e-mail that an Iranian cleric called on all Shiites and Muslims to find him and kill him.
Death threats against the rapper multiplied, culminating in a bounty of $100,000 on the rapper's head.
"When I first saw the price on my head online, the $100,000, I really understood that it had got serious," Najafi said.
The rapper is currently under German police protection.
His manager said he has filed an official complaint against the cleric who accused him of apostasy, a crime punishable by death in Iran.