The Vatican said he received ice treatment and was fine to continue on his trip.
Video images showed the pope hitting the left side of his face against a vertical bar of the popemobile, a specially designed open-top vehicle that allows the pontiff to stand and greet the faithful as his motorcade advances.
A few drops of blood were seen on his white cassock and the area around his left eye looked bruised and swollen.
He later was seen with a small bandage over his left eyebrow.
"The pope is fine. He injured his left cheekbone and eyelid," spokesman Greg Burke said.