According to the Daily Express and the German Main-Spitze news site, the children attacked the 47-year-old Ethiopian priest, who was with a fellow clergyman, in Raunheim near Frankfurt.
The pair, who haven't been named, were wearing religious robes and crosses on their way to a Russian Orthodox chapel in Raunheim when the incident happened earlier this week.
The boys, believed be to no older than 12, ran away before the clergymen could take photographs of them on their mobile phones.
Dr Isack Majura, a social worker in the town, told Main-Spitze: "What happened is absolutely unacceptable."
Premier has contacted Hessen Police for more details.
