Egyptian officials, including the foreign minister, have acknowledged coordination exists between ISIL and other militant groups, including ones in Egypt, but have said there are no Islamic State fighters in the country.
Egypt has faced insurgents since the army toppled President Mohamed Mursi of the Muslim Brotherhood last year, Reuters reported.
"Rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads. Do not let them feel secure," ISIL spokesman Abu Muhammad al-Adnani said in a statement to Egyptian militants released online.
He praised those militants for carrying out "blessed operations against the guards of the Jews, the soldiers of Sisi, the new Pharaoh of Egypt" - a reference to Egyptian President Abdel Fattah el-Sisi who succeeded Mursi.
Sinai-based militant group Ansar Bayt al-Maqdis, which has killed hundreds of Egyptian security forces over the last year, beheaded several people in recent weeks, saying they were spies for Israeli intelligence.