"Wherever you are in New Zealand, or around the world, this is a moment we can stand alongside those who have lost loved ones in this extraordinary tragedy," Xinhua news agency quoted Ardern as saying.
"Together we can express our sorrow for those who have died and been hurt, and our support for their grieving families and friends".
The minute's silence at 2.11 p.m. will be exactly a week after the eruption that took place on December 9 and claimed the lives of 16 people.
Meanwhile, operation to search and recover the last two victims who remain missing, continued in the waters around White Island on Saturday morning.
Additional personnel from the Navy dive team will be deployed to boost the operation, said New Zealand Police Deputy Commissioner John Tims.
A team of nine from the Police National Dive Squad also resumed their search.
However, the water around the island is contaminated, requiring the divers to take extra precautions to ensure their safety, including using specialist protective equipment, said Tims.
Conditions in the water on Saturday were not optimal, with between zero and two metres visibility depending on location, said Tims.
Six bodies were successfully recovered from the volcano island during Friday's operation.
On Saturday, the risk had since been downgraded with tremors slowing down. GNS volcanologist Brad Scott told local media the tremors "declined significantly overnight".
Fifteen victims remain in New Zealand hospitals, 11 of which were in a "very critical condition with extensive severe burns", according to Counties-Manukau Health chief medical officer Dr. Peter Watson.
The White Island, a volcanic island, is a famous tourist attraction which people can explore by boat or by helicopter. If safety conditions permit, visitors can even enter the main volcano crater.
( With inputs from IANS )