The quake struck 110 kilometres north-northeast of the town of Tobelo in the Maluku chain of islands around 1330 GMT at a depth of 63 kilometres, the US Geological Survey said.
Technical chief at Indonesia's Meteorology, Climatology and Geophysics Agency Suharjono, who goes by one name, said there was no threat of a tsunami.
A hotel owner in Tobelo said guests ran from their rooms as the quake shook the ground for a few seconds, but no damage was seen in the area.
"It was quite strong actually, but it didn't last too long and everything appears to be back to normal," Edwar said.
Indonesia sits on the Pacific "Ring of Fire" where tectonic plates collide, causing frequent seismic and volcanic activity.
A 6.1-magnitude quake that struck Aceh province on Sumatra island in July killed at least 35 people and left thousands homeless.