The quake's depth at 347.7 miles (560 km) would have dampened the shaking at the surface.
Officials at the National Tsunami Warning Center said the quake struck the Fiji Islands region Saturday afternoon, but no Pacific-wide tsunami threat was generated.
No injuries or damage were immediately reported.
The Hawaii-based Pacific Tsunami Warning Center said there was "no tsunami threat because the quake is located too deep inside the Earth".More news: Sarri identifies exactly where Chelsea need to improve after win over Arsenal
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"We are monitoring the situation and some places felt it, but it was a very deep natural disaster", Director Apete Soro said by telephone.
A magnitude 7.0 quake on August 5 damaged tens of thousands of homes and displaced several hundred thousand people on Lombok.
The epicenter was located 270km east of Levuka in Fiji and 443km west of Neiafu in Tonga.
Indonesia sits on the Pacific Ring of Fire and is regularly hit by earthquakes.