"There is no longer a tsunami threat from this earthquake," the NWS said in a statement.
Papua New Guinea is located in a seismically active zone known as the Ring of Fire and regularly suffers from powerful earthquakes.
Earlier on Friday, the US Geological Survey said that the tremor had been recorded at 02:50 GMT, 114 kilometres (about 71 miles) northwest of the city of Popondetta in the Oro Province. The epicentre of the earthquake was located at a depth of 79.8 kilometres.
The NWS announced a tsunami alert following the earthquake.