The temblor hit around 100km (62 miles) northeast of the main island early on Monday, local time, according to the U.S. Geological Survey.
The quake struck six miles deep, which is far shallower than the 18-mile deep Boxing Day tsunami.
But a shallow quake shakes the ground more severely, meaning the likelihood of a major tsunami is increased.
Hazardous waves could be possible for coasts within 300km (185 miles) of the quake’s epicentre, according to the Pacific Tsunami Warning Centre.
No reports of damage were immediately available, as the quake struck in the middle of the night.
A geolocator showing the exact location of the earthquake that struck Tonga's coast
Tsunami warning after huge 7.1 magnitude earthquake hits Tonga's coast
Tonga is a country in Polynesia. It is made up of 171 islands and home to 100,000 people, most of whom live on the island of Tongatapu.
The country is more than 3,500km (2,000 miles) from Australia's east coast.
It comes as a powerful 7.7 magnitude earthquake hit Myanmar on Friday, with the death toll passing 1,600 in Myanmar and neighbouring Thailand.
State television in Myanmar confirmed that 1,644 have died - a sharp rise over the 1,002 total announced just hours earlier, underlining the difficulty of confirming casualties over a widespread region and the likelihood that the numbers will continue to grow.
The US Geological Survey and Germany 's GFZ centre for geosciences said the quake struck at a shallow 6.2 miles below the surface, before a second quake, with a magnitude of 6.4, shook the area 12 minutes later.
A state of emergency has now been declared in six regions and states in Myanmar by the military-run government.
