The shallow quake hit around 11:30 pm local time (1230 GMT) around 27 kilometres (17 miles) deep, said the USGS, which placed it about 25 kilometres from the village of Port-Olry.
“Tsunami waves reaching 0.3 to one metre above the tide level are possible for some coasts of Vanuatu,” the NWS Pacific Tsunami Warning Centre in Hawaii said.
Waves smaller than 0.3 metres were possible for New Caledonia and the Solomon Islands, it added.
Vanuatu is part of the Pacific “Ring of Fire”, where tectonic plates collide, and it experiences frequent seismic and volcanic activity.
Solomon Islands, a nearby island nation just north of Vanuatu, was in November hit with a strong 7.0 quake, though there were no reports of serious injuries or major structural damage.
Eyewitnesses reported violent shaking that hurled items to the ground and knocked out power in parts of the capital Honiara.
The coastal regions of Vanuatu and nearby Papua New Guinea was put on alert for tsunami waves of up to 30 centimetres (12 inches).