Police officers were called to the scene and have begun an investigation, Israeli broadcaster Arutz Sheva reported.
The incident is not the first time the school has been covered with anti-Semitic symbols, police said.
Member of the Knesset Eli Yishai has blamed anti-hareidi inciters, who are against the most conservative form of Judaism.
"I urge the police to bring those responsible to justice, and I demand that politicians realize that their behavior, and their statements, have results," he said.
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