Al-Gamaa Al-Islamiya and its political arm the Building and Development Party has condemned recent attacks on Egypt's army and distanced itself from periodic violence widely blamed on Islamists.
On Wednesday, the Islamist group said it followed "with great concern the assaults on military personnel."
The comments came a day after gunmen killed an officer and a soldier in an attack on an army vehicle in the Nile Delta's Sharqiya governorate.
Egypt's Sinai Peninsula, adjoining Israel and the Palestinian Gaza Strip, has seen a militant insurgency since the army's popularly backed overthrow of Islamist president Mohamed Morsi on 3 July, heightening fears that militant violence could spill over elsewhere in the country.
The group, which enjoys a strong base of support in Upper Egypt, said it "renews [its] rejection and condemnation of such attacks, which some employ to provoke a dispute between the armed forces and Islamists."
It reiterated calls for peaceful protests against the "coup, in a way that secures a political solution … and maintains the army's strength."
Al-Gamaa Al-Islamiya members were convicted of terrorist attacks in the 1980s and 90s, including the 1981 assassination of president Anwar Sadat. It is notorious for a 1997 attack that killed 58 tourists in Luxor.
The group, which renounced violence more than a decade ago, vowed in August not to use to violence and to come down hard on any member guilty of attacking police, soldiers or Christians.
The group's leading figures, Assem Abdel-Maged and Tarek El-Zomor, along with several dozen other activists, have been sought by police over allegations of inciting violence.
A wave of detentions has netted the leadership of Morsi's Muslim Brotherhood along with at least 2,000 other Islamists.