The Muslim Brotherhood's supreme guide, Mohamed Badie, says that dialogue is the only way of dealing with disagreements with the opposition. Reuters

The Egyptian military has urged rival political forces to solve their disputes via dialogue and save the country from being dragged into a "dark tunnel" of increasing violence.

A statement from a military spokesman was read out on state radio and television made no mention of President Mohamed Morsi, whose contentious draft constitution and decrees granting himself extraordinary powers and judicial immunity sparked days of violence. But it said a solution to the political crisis should not contradict "legitimacy and the rules of democracy".

The spokesman said the military's duty was to protect national interests and secure vital state institutions. "The armed forces … realise their responsibility to preserve the higher interests of the country and to secure and protect vital targets, public institutions and the interests of innocent citizens," the statement said.

"The armed forces affirm that dialogue is the best and only way to reach consensus," it added. "The opposite of that will bring us to a dark tunnel that will result in catastrophe and that is something we will not allow."

The military's attempt to defuse the political crisis came as the spiritual leader of Morsi's party, the fundamentalist Muslim Brotherhood, also urged Egyptians to disown violence, saying that working through the ballot box was the best way to lift the country out of its turmoil.

Brotherhood "supreme guide" Mohammed Badie said on Saturday morning that the group's supporters did not initiate the violent clashes outside the presidential palace in which at least seven people died and 700 were injured.

Morsi has called for a meeting with his opponents to discuss the crisis. The opposition has rejected talks, saying Morsi must first cancel the referendum on the draft constitution set for 15 December.

Mohamed ElBaradei, the opposition National Salvation Front's chief co-ordinator and a Nobel laureate, called on opposition groups to shun dialogue with Morsi. We want "a dialogue not based on an arm-twisting policy and imposing fait accompli", he said on Twitter. George Ishak, another opposition leader, said: "Whoever has killed his own people has lost legitimacy."

Morsi insists the decree is necessary to end Egypt's turbulent transitional period and that his special powers would lapse once the new constitution was passed. Critics complain that his powers exceed even those wielded by the deposed Hosni Mubarak, who ruled for nearly 30 years.