Supporters and opponents of ousted Egyptian President Mohamed Morsi plan rival mass protests on Friday, raising fears of continued violence.
Army chief Abdel Fattah el-Sissi has called for "all honorable Egyptians" to take to the streets to give him a mandate to fight what he called "violence and terrorism."
Many Islamists view the statement as a prelude to a violent crackdown and have called for their own protests. Egypt's army has recently used "violence and terrorism" to refer to the actions of Mr. Morsi's Muslim Brotherhood.
A military spokesman insists Sissi's statement was not aimed at any single political group. While he says the military respects peaceful protests, he vowed that any violence will be dealt with "decisively and with force."
Since the military's removal of Mr. Morsi on July 3, more than 100 people have been killed during confrontations with authorities and between pro- and anti-Morsi factions.
World leaders are expressing increasing concern about the rising violence and polarization of Egyptian society.
On Thursday, United Nations Secretary-General Ban Ki-moon called for restraint on all sides, saying he supports the rights of all Egyptians to hold peaceful protests.
He also said the Egyptian military should "end arbitrary arrests and other reported forms of harassment." He said Mr. Morsi and other detained members of the Muslim Brotherhood should either be freed or have their cases reviewed.
Washington has also expressed concern about Sissi's calls for protests. Hours after the Wednesday speech, the Obama administration announced it had delayed the delivery of four F-16 fighter jets to Egypt's military.
But on Thursday, the White House delivered what could be considered a victory to Egypt's army by announcing it will not declare its overthrow of the government as a coup. Such a designation would have required the U.S. to suspend its massive military and economic aid to Egypt.
The army has denied accusations that its move represented a coup. It says it was obligated to remove Mr. Morsi, Egypt's first elected president, following days of large protests against his rule.
The Egyptian military dominated Egyptian politics for decades until the 2011 overthrow of ex-military general and president Hosni Mubarak. It has a long history of animosity toward the Muslim Brotherhood, which is Egypt's most organized political party.