Duncan Garner has condemned the deadly use of force against protesters in Gaza, saying we "shouldn't downplay" what has unfolded.
The AM Show host added that "pig-headed" Americans who wanted the embassy moved to Jerusalem from Tel Aviv are partly to blame for the incidents of the past 24 hours.
At least 52 people were killed at the border between Gaza and Israel, with 2400 more injured on Monday (local time), as thousands protested against the opening of the embassy.
- Israeli forces open fire on Palestinian protesters, at least 50 dead
- Jacinda Ardern condemns 'devastating one-sided loss of life' in Jerusalem
"They're assassinations aren't they?" Garner said on Tuesday morning.
"They're snipers with probably the instruction of shoot. These guys know what is going on. They know they're going to rush the fence, so they shoot. And 52 people - and it could be more - have died, have been shot and killed.
"And the Americans were so pig-headed and willing to open this Embassy."
Garner says he doesn't understand why other options - such as water cannons, rubber bullets or tear gas - weren't used.
"I mean, the Israelis have more weapons than anybody else when it comes to this sort of thing," he went on.
"I think they were acting under instruction and I think the Palestinians have every right to say, 'Hang on, this is a crime'.
"This is a war crime and this needs to be investigated. There needs to be a proper international investigation."
When US President Donald Trump announced last year its embassy would move to officially recognise Jerusalem as Israel's capital, the NZ Government said that would "make things difficult".
"We said that this would lead to a backwards step in the progress towards peace, and it has," Ms Ardern told Newshub on Tuesday morning.
"This is the most significant violence we've seen in a number of years."
Monday marks the highest Palestinian single-day death toll since the 2014 Gaza war.
The AM Show co-host Amanda Gillies added Mr Trump, as of midday Tuesday (NZ time), "has said nothing about" the deaths.
"They weren't armed, they were shot at; 52 dead - that's huge. The only defence they had at the time was they were burning tyres so that they would smoke so that they could be lost in the smoke as some sort of defence.
"And what happens now? There's going to be a fight-back. There's going to be retaliation."
Co-host Mark Richardson said "that pig-headedness, that, 'No you can't tell us what we can and can't do' has led to what is some pretty shameful scenes".
"And whether you think that in America they think they have a right to the US Embassy or not, sometimes you have to go you know what, it's probably not worth it, let's not do it."