Israeli police have detained two teenagers who are suspected of inadvertently starting the blaze, which killed 41 people, by leaving a bonfire unattended.
Ovadia Yosef, the spiritual leader of Shas, a powerful religious party in Israel's coalition government, said there was little doubt that the fire was sent by God to punish his chosen people for their waywardness.
In his weekly sermon, the rabbi quoted a section from the Talmud, a central Jewish religious text, which proclaimed that "the fire only exists in a place where the Sabbath is desecrated".
"Homes were ruined, entire neighbourhoods wiped out, and it's not arbitrary," he said. "It is all divine providence. We must repent and keep the Sabbath properly."
Rabbi Yosef also predicted that God would only heal the scorched earth of Mt Carmel, where more than 10,000 acres of forest were destroyed, when the people of Israel came to their senses.
For many ultra-orthodox Jews in Israel, Rabbi Yosef is the most important religious authority in the land and his comments drew little criticism from government officials wary of upsetting a powerful coalition partner.
The Israeli press was more hostile, forcing Eli Yishai, the interior minister and political leader of Shas, to defend his colleague.
"The rabbi preaches morals to all of us in order to gain strength, to do good deeds and to repent," he said.
Mr Yishai has faced calls to resign amid accusations that his ministry failed to heed calls for more funding and better equipment for the country's overstretched fire service.
Forced to appeal for international assistance, Israeli firefighters said the forest fire had finally been brought under control on Sunday afternoon. Firefighting aircraft from around the world, including two RAF helicopters, have been fighting the blaze, which claimed most of its victims after a bus carrying prison service cadets became trapped in the flames.
