The temblor, which hit at a depth of 34 kilometres at the New Zealand-administered volcanic island group, was some 870 kilometres from the nearest major city Whangarei, in New Zealand, according to the US Geological Survey.
"Based on all available data a destructive Pacific-wide tsunami is not expected," the Hawaii-based Pacific Tsunami Warning Center said.
The Kermadec Islands are located roughly equidistant to New Zealand's North Island and the Pacific nation of Tonga, and are uninhabited except for a permanent weather, radio and conservation station on Raoul Island.
The Kermadecs frequently see large tremors, including three quakes in excess of 7.0-magnitude in 2011.