Egypt's army chief has called for demonstrations on Friday to give the military a mandate to confront "violence and potential terrorism".
Abdel Fattah al-Sisi said he was not calling for public unrest and wanted national reconciliation.
The army removed President Mohammed Morsi from power on 3 July, triggering huge street protests by his supporters.
In another development yesterday, the US said it was delaying the sale of four F-16 military jets to Egypt.
Washington has said it is examining whether the military takeover constitutes a coup, as US law prohibits the sending of aid to any country whose elected leader is deposed by a military coup.
The Muslim Brotherhood and other supporters of Mr Morsi say they will go ahead with their own rallies on Friday, despite General Sisi's statement.
Senior Brotherhood figure Mohamed el-Beltagy said Gen Sisi was "calling for a civil war... to protect this military coup".
Gen Sisi's comments are provocative, confrontational, and unprecedented.
It's a call to action, and the target is clearly the Muslim Brotherhood. Its leaders say the call is a threat, and are refusing to budge in their demand for President Morsi's reinstatement.
But Gen Sisi's call has been backed by Tamarod, the rebel movement that co-ordinated the protests in June which brought millions onto the street and resulted in President Morsi's removal. They say it's the army and the people against terrorism – but this is clearly the army and some of the people against the Muslim Brotherhood.
Over 100 people have already died in fighting, mostly in Cairo, since the crisis began. Perhaps it shows the military's anger over last night's bombing of a police station in the city of Mansoura, which left one soldier dead, and a dozen policemen injured. Or it may reflect their frustration at President Morsi's supporters' refusal to disappear.
This latest intervention by the military makes it more difficult for them to deny the plain fact of who is running Egypt. It doesn't appear to be the interim President Adly Mansour – it is the man whose portrait is plastered on walls and kiosks around Cairo: Gen Abdel Fattah al-Sisi.
"He is proving that he is the actual ruler of the country, and that the president, his vice president and the government do not hold any power," he added.
In a speech at a military graduation ceremony, which was broadcast on television, Gen Sisi said: "I urge the people to take to the streets this coming Friday to prove their will and give me, the army and police, a mandate to confront possible violence and terrorism."
"So that in case there was a resort to violence and terrorism, the army would have a mandate to confront this."
Our correspondent says that Gen Sisi's call showed who was really in charge in Egypt – not the interim president picked by the military, Adly Mahmud Mansour, but the military itself.
He says it may be a sign of frustration that protests against the interim government are still going on.
It also followed an overnight bomb attack on a police station in Mansoura, 110 km (68 miles) north of Cairo, that killed one person and wounded two dozen others.
A government spokesman condemned it as a terrorist attack.
In Cairo, two people were reported to have been killed in clashes at a pro-Morsi demonstration overnight. That followed nine deaths in the city on Tuesday.
Gen Sisi, who is also the defence minister in the new government, rejected rumours about divisions within the army ranks. "I swear by God that the Egyptian army is united," he said.
Referring to the army's intervention to remove Morsi early this month, Gen Sisi said: "I urged the former president to be a president for all Egyptians".
National Mirror
Street protest would definately make a lot of sense in a country like Egypt. I think they are pretty used to protests as at now..