Egypt's foreign ministry spokesman Ahmed Hafez described the bomb attack on a tourist bus near the Giza pyramids on Friday as a "cowardly, terrorist act".
Prosecutor-General Nabil Sadek said on Friday evening that four people had died in the IED attack on the bus carrying Vietnamese tourists, including three Vietnamese and one Egyptian.
"The bombing of the tourist bus in Mariouteya is a cowardly act of terrorism targeting what cannot be targeted: Egypt and the Egyptians," Hafez wrote on Twitter.
"We express our sincere condolences to the families of the victims in Vietnam and Egypt. We will continue to move towards a new year of determination to root out terrorism."
Sadek had said that the number of injured stood at 11.
The bus was in the Haram district near the pyramids; 14 Vietnamese tourists and two Egyptian workers were on board.