Egypt said that Syria's territorial integrity must be preserved – an apparent sign of its disapproval of Turkey's intervention against militants in Iraq and Syria.
The Foreign Ministry said in a statement on Tuesday that Cairo supported combating what it called terrorist groups in Syria.
But this effort must happen "within the context of preserving the unity and integrity of Syria's territories…in accordance with international legal norms and decisions," it said.
Turkey last week began bombarding targets in Syria linked to the Islamic State jihadist movement and granted access to its air bases to a US led-coalition — ending a policy which avoided direct intervention in the Syria conflict.
It also struck militants from the Kurdistan Workers Party (PKK) in Iraq in recent days in response to attacks against its security forces.
Washington and Ankara also announced plans to sweep Islamic State fighters from a strip of land along the border, possibly providing a safe haven for civilians.
The Egyptian statement did not elaborate nor mention Turkey.
Political analyst Hassan Abou Taleb of Al Ahram Centre for Political and Strategic Studies said Egypt's message was a "condemnation and rejection of Turkey's unilateral moves".
Egyptian President Abdel Fattah al-Sisi, who is fighting an Islamist militancy in the Sinai, has stressed the need to maintain Syria's unity in the past.
Various countries, including the United States, support rebels fighting to bring down President Bashar al-Assad. But the conflict has seen a proliferation of jihadist groups opposed to both Assad and the West, and the fragmentation of the country.
Four years into a war that has killed more than 220,000 people, Assad can no longer defend the whole country or hope to regain lost territory and his forces are retreating and fortifying their core strongholds, from the capital Damascus up to the coastal strip in northwestern Syria.
At the same time, the main blocs of insurgents — Islamic State in the east, a rival Islamist alliance in the northwest, nationalist rebels in the south and Kurds in the north — are carving out their own fiefdoms.
Sisi is also worried about Islamist militants in neighbouring Libya, which has descended into chaos since autocrat Muammar Gaddafi was toppled in 2011.
Egypt intervened in Libya in February when it bombed Islamic States targets there after the militant group beheaded 21 Egyptian Christians.
