Umar Ibrahim Kabo, the chairman of the council of Ulama in the northern city of Kano, said Muslims were tired of "perennial massacres" and hinted that Plateau State Governor Joshua Dariye was failing to act.
"We hereby give a seven-day ultimatum to President Obasanjo to take effective measures to bring these killings to an end or bear the blame of whatever happens after the ultimatum."
Kabo, who is also head of Kano State's influential Sharia Commission, even alleged the Shendam killings were part of a global Western war against Islam.
"Dariye is being used by the west to execute a long-planned genocide against Muslims in Nigeria, beginning in Plateau State," he alleged.
On Sunday last week, a heavily armed gang of militants from the Christian Tarok ethnic group stormed the mainly-Muslim rural town of Yelwa, in the Shendam local government area of central Nigeria's Plateau State.
They killed between 200 and 300 people, according to government figures.
The attack has raised fears of a Muslim backlash in a country where more than 10,000 people have died in mob violence since the return of civilian rule in 1999 and where relations between Muslims and Christians - which make up about half each of the 130-million strong population - are often tense.
Over 630 Muslims died in a killing
spree in September 2001
Effigies of US President George Bush, Israeli Prime Minister Ariel Sharon and Governor Dariye were burned while the protesters marched on the office of Kano's Islamist governor, Ibrahim Shekarau.
"We are ready to live in peace and be law-abiding, but if our lives and honour are violated we are ready to law down our lives to protect them," he said.
He also called on his supporters not to take out their frustrations on "the innocent".
The Hausa community in Yelwa, whose leaders claim that more than 600 people were killed in last week's attack, have accused federal security forces of failing to protect them from heavily armed attacks.
Many suspect there is a plot to drive them from the religiously mixed state.
Both Dariye and Obasanjo's government has firmly denied that there was any collusion between police and the attackers, and 600 additional officers have been deployed to the Shendam area in order to prevent further bloodletting.