The Egyptian Cabinet said in a news release that 13 victims of Friday's attack remained hospitalized in Cairo and the southern province of Minya where the attack took place.
The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group claimed responsibility for the April attacks. "Egypt will not hesitate to target these terror camps anywhere", Sisi said in a televised speech aired by the state TV.
The statement from the military spokesman did not specify precisely where the strikes were conducted but state television said on Friday that operations were focused on the eastern Libyan city of Derna. Witnesses there reported four strikes by a single aircraft.
"The bloodletting of Christians must end, and all who aid their killers must be punished", he said in a statement issued by his press office as he attends the G7 summit in Taormina, Italy.
No one has yet claimed credit for Friday's attacks, but both the previous attacks were claimed by the Sinai terror group called Ansar Bayt al-Maqdis (ABM - Ansar Jerusalem - Champions of Jerusalem).
The group was today travelling in two buses and a small truck in Minya province, which is home to a large Christian minority, the sources said.
"They want to send a message to the Christians that the government can not protect you. we must be careful", he said.
Egypt's Foreign Minister Sameh Shoukry told his U.S. counterpart Rex Tillerson that the jihadists who attacked the Christian convoy had trained in Libyan militant camps.
The head of the Coptic Christian Church, Pope Tawadros, who spoke with Sisi after the attack, said it was "not directed at the Copts, but at Egypt and the heart of the Egyptians". The Grand Mufti of Egypt, Shawki Allam, condemned the perpetrators as traitors.
Coptic Christians make up about 10% of Egypt's population of 91 million.
There have been a number of attacks on Coptic Christians in the country in recent months claimed by Islamic State militants.
It has also killed several Christians in North Sinai, forcing dozens of families to flee.
Two suicide bombings at Palm Sunday services at churches in the northern cities of Alexandria and Tanta on 9 April left 46 people dead.
It's unclear whether Friday's attack is related to that warning.