The quake was just 10km deep and about 155km east-southeast of the Loyalty Islands, the Pacific Tsunami Warning Centre said on Wednesday.
Authorities in the South Pacific territory urged people to move to locations more than 300 metres distant from the shore, and if possible, to sites higher than 12 metres above sea level.
“We have set off the alarm on the exterior of New Caledonia but we don’t have any immediate assessment of potential damage,” said a spokeswoman for the Directorate for Civil Protection and Risk Management.