"We appeal to all Lebanese, from every region and political movement, to take part in a peaceful and civilised demonstration on Friday to rid us of an incapable government that has failed in its mission," he said.
Marwan Hamadeh, Lebanon's communications minister, reiterated that the pro-Western government will not give in to opposition demands.
"We are going to take to the streets peacefully"
Michel Aoun, head of a Christian opposition group
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"The government will not give in. It rests on a comfortable majority in parliament and among the people and has the support of the Arab world and the international community, apart from Syria," Hamadeh said.
"Lebanon faces a choice of system - democracy or religious autocracy."
Fouad Siniora, Lebanon's prime minister, later appealed to the Lebanese to rally behind his government in a televised address.
He said: "We will not allow the overthrow of the democratic system, its foundations and its institutions ... We are staying in our place.
"Lebanon's independence is threatened and its democratic system is in danger.
"Do not be afraid and do not despair. We have a rightful cause. Threats will not deter us. Manoeuvres and ultimatums will not terrorise us."
Michel Aoun, the head of a Christian opposition group, also called for his supporters to take to the streets to demand the formation of a new national unity government in Lebanon.
Aoun, an ally of Hezbollah, said: "We are going to take to the streets peacefully. The other camp is obliging us to do this.
"I call on all Lebanese to take part in this movement against the [anti-Syrian] government of Prime Minister Fouad Siniora ... there is still a path open to solutions."
The call for demonstrations came after weeks of political tension between pro-Syrian groups and anti-Syrian factions over the formation of a unity government and the assassination of Pierre Gemayel, the Lebanese industry minister.
Meanwhile, Michel Sleiman, the Lebanese army chief, has called on his men to "stand ready" to maintain public order in case of mass demonstrations in Beirut.
In a statement he said: "I call on all soldiers to stand ready to maintain freedom of expression while preventing disturbances to public order."
"The army will not tolerate any damage to public property or any clashes. It considers it stands at an equal distance from both sides," Sleiman said, referring to the deep rift between the groups.
"In contrast to the situation on the eve of the outbreak of civil war in 1975, where the army was neutralised by political divisions ... today it stands united and enjoys the trust of the people."