There were no casualties after two explosions went off in the space of two minutes in the center of the Egyptian capital on Friday, Egyptian television said Al Arabiya reported.
Residents told Agence France-Presse that the blasts were followed by ambulance sirens.
The local Youm7 newspaper also reported that two blasts targeted vehicles belonging to the Egyptian security forces at al-Giza bridge in Cairo.
Egypt has seen a wave of attacks claimed by jihadist groups since the arm removed its first freely elected president, Islamist Mohammad Mursi, last year and cracked down on his supporters.