The Bernama news service reports the jolt occurred at 12:54 a.m. local time and shook the Central Sulawesi Province city of Tolitoli.
One resident there told the agency that the shaking was so powerful that people who were standing at the time were tossed around.
Many people rushed outside in fear that the buildings would collapse, Bernama said.
But, there were no immediate reports of significant damage or any injuries due to the shaking.
While Indonesia's seismic service said Monday's quake had a magnitude of 6.5, the U.S. Geological Survey assigned it a magnitude of 5.9 and said it occurred 90 miles (140 km) northeast of Palu, Indonesia, at a depth of 73 miles (117 km).