The U.S. Geological Survey said in a posting on its Web site that the quake was 6.4 magnitude.
The quake, at a depth of 37 km (23 miles), had its epicenter 182 km (113 miles) west of Jayapura in eastern Indonesia, USGS said.
USGS had earlier said the quake was 6.6 magnitude.
An official at Indonesia's Meteorology and Geophysics Agency said there was a weaker aftershock after the initial quake, but there were no immediate reports of damage.
"The quake was pretty strong. If it had struck a village or a town it would have had an impact," Suhardjono, an agency official, said by telephone.
Strong quakes are common in this part of Indonesia, but most strike the unpopulated highlands of the remote area.
The Indonesian agency said the quake measured 6 on the Richter scale and was followed by an aftershock of 5.3.
"So far we have not received any reports (of casualties or damage) but the quake was mildly felt in parts of Jayapura." Indonesia suffers frequent earthquakes, being located in a very active seismic region where several tectonic plates meet.