Two bombs exploded on Tuesday at al-Zahraa and al-Sayyeda Zeinab metro stops.
Informed security sources said the bombs were thrown from outside the metro walls, causing no losses or injuries.
Speaking on condition of anonymity, the sources said that police combed the areas around the two stops in search for other bombs.
Blasts targeting security elements and public facilities have increased since the ouster of deposed president Mohamed Morsy.
The Muslim Brotherhood denies accusations of being behind the blasts that claimed the lives of dozens of police and military personnel.
Edited translation from Al-Masry Al-Youm