The 4.5 magnitude jolt occurred near the coast of Lipari, the main island in the Aeolian chain between Sicily and the Italian peninsula.
The shaking also sent a rockslide cascading toward a crowded beach, but it stopped short of reaching any people.
Two of the injured who went to the hospital were bitten by jellyfish after jumping into the sea when the rockslide occurred, according to the Ansa news agency.
Shaking was also felt along the northern coast of Sicily, including the main city of Palermo.
The Aeolian island chain is a volcanic archipelago and is a popular tourist destination, especially during the peak summer holiday season in August.
It’s home to Stromboli, one of the world’s most active volcanoes.