The country launched a fresh round of airstrikes over Libya on Saturday, targeting militant camps it said were responsible for the attack on the bus convoy as it travelled to a monastery south of Cairo.
Sameh Shoukry, Egypt’s foreign minister, said “there was enough information and evidence of the terrorist elements involved in the (attack) having trained in these camps.”
Islamic State said it carried out the attack – the latest in a series against Coptic Christians that has seen more than 100 people killed since December.
Masked gunmen in three pick-up trucks attacked the convoy as it headed for Saint Samuel monastery, before fleeing the scene.
Military sources said airstrikes took place in the area of Derna, eastern Libya, where forces led by close Egypt ally Khalifa Haftar has been trying to seize control.
The area is controlled by jihadists close to al Qaeda.
In a statement, it said it had “conducted several intensive day and night-time strikes” that successfully destroyed targets including training camps.
Egypt has repeatedly expressed concern over militants crossing from Libya to carry out attacks.
On Friday, Egypt President Abdel Fattah el-Sisi said setbacks to IS in Syria were driving its fighters to try to relocated to Libya and Sinai.
Last month, two suicide bombings killed 45 Coptic Christians at churches.
And in December, a suicide bomber killed 29 people at a church in Cairo.
Libya’s militant strongholds have come under further scrutiny since Monday’s terror attack in Manchester, which left 22 dead.
Suicide bomber Salman Abedi, the British-born son of Libyan parents, is believed to have recently visited the north African country before carrying out the attack on a pop concert.