Tsunami waves were observed in Tonga's capital and the capital of American Samoa, a U.S.-based tsunami monitor said.
The eruption at 0410 GMT of the Hunga Tonga-Hunga Ha'apai underwater volcano, located about 65 km (40 miles) north of Nuku'alofa, caused a 1.2 meter tsunami, Australia's Bureau of Meteorology said.
The agency said it continued to monitor the situation but no tsunami threat had been issued to the Australian mainland, islands or territories.
Tsunami waves of 2.7 feet (83 cm) were observed by gauges at the Tongan capital of Nuku'alofa and waves of 2 ft at Pago Pago, the capital of American Samoa, the Pacific Tsunami Warning Center said.
The U.S.-based monitor later canceled warnings for the U.S. territory of American Samoa and Hawaii, but said the tsunami remained a threat for parts of the Pacific nearer the volcano.