The undersea quake hit about 300 kilometres (185 miles) south of the popular holiday island of Lombok at 12:13 pm (0413 GMT), at a depth of 29 kilometres, said the US Geological Survey.
Indonesia's disaster agency said officials were checking to see if the quake had any impact.
Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire," where tectonic plates collide.