He has stressed that he has made the announcement as Labour leader, not caretaker Prime Minister.
But Hipkins said it had become "untenable" for him to remain silent.
"It runs against Labour Party values to see the horrific scenes we are witnessing without calling for a ceasefire," he said.
"Israel and Gaza need to immediately ensure that conditions for a ceasefire be met. We call on all parties to strive to restore calm and restraint.
"We remain very concerned about the humanitarian impact of the conflict."
Hipkins has called on Israel to allow supplies to be delivered.
"Ultimately we want to see a just and lasting peace.
"The violence and the killing has to stop."
Israel has vowed to annihilate the Hamas militant group that controls Gaza, since its fighters killed 1200 people and dragged away 240 hostages on a deadly rampage on 7 October.
Since then, Israel has bombed much of Gaza to rubble.
Gaza authorities say more than 12,000 people are confirmed dead, 5000 of them children, with many others trapped under rubble.
"Ultimately, we want to see a just and lasting peace that recognises the existence and self-determination of Israelis and Palestinians," said Hipkins.
"We encourage the parties to work towards a two-state solution within secure and recognised borders where all citizens enjoy equal rights and freedoms."
Israel had a right to defend itself, "but that right is not unlimited", Hipkins said.
"Hospitals should never be used for military purposes, but neither should hospitals be attacked," he said of the current action against hospitals in Gaza.
"Experience would suggest that militarily trying to eradicate terrorist organisations isn't a route to success."
The caretaker government had sought agreement from the opposition before calling for a ceasefire, but did not get it, Hipkins said.
"I would prefer New Zealand to be more assertive in the position we have been taking," he said.
Asked if the incoming government was diminished on the world stage during the current period, Hipkins said he was not going to speak for them.
"I think the New Zealand public's concern is pretty evident. We can see the images on the news at night. We can see civilians, children, being killed, and we want that to stop.
"Five weeks is a long time to continue to stay silent on an issue that's as important as this one."
- RNZ w/Reuters
