The terrorist group said it carried out the attack near the Italian diplomatic mission in the Egyptian capital.
On Saturday, a car exploded in front of the consulate, killing one person and injuring at least nine. No Italian citizens were hurt in the attack.
Italian Foreign Minister Paolo Gentiloni said earlier in the day that the explosion was an attack against Italy. The country's prime minister, Matteo Renzi, said Rome and Cairo would continue working together to counter terrorism.
Sources in Egypt's prosecutor's office told local Masrawy news website that the type of explosives used in Saturday's explosion was similar to last week's deadly attack on the country's prosecutor general,Sky News reported.
The murder of the official took place after an ISIL affiliate in Egypt published a video threatening judicial officials in the country.