The Palestinian group Hamas, which rules the Gaza Strip, has condemned the killing on Monday of at least 42 Egyptians at a Cairo sit-in.
Hamas said Monday that it "voices extreme pain and grief" for the victims' death. It sent condolences to the victims' families.
The Palestinian Islamist group is an offshoot of the Muslim Brotherhood, the movement of toppled Egyptian President Mohammed Morsi.
Egyptian soldiers and police clashed with supporters of the ousted president early Monday in violence that left at least 42 people killed, including one officer.
Gaza borders Egypt and Hamas had made important gains with Morsi in power. With his ouster, it is likely to suffer setbacks. Since Morsi was deposed last week, Egypt has shut a key land crossing for Gaza indefinitely, citing security concerns.