New Zealand's Prime Minister John Key is being urged to make public the briefings he's had on the Syrian crisis, and what action the United States plans to take.
Mr Key spoke with Australian Prime Minister Kevin Rudd on Wednesday afternoon and is due to speak with other leaders, including Secretary-General Ban Ki-moon and British Prime Minister David Cameron, this week.
New Zealand's UN diplomats were also due to be briefed by US officials on Wednesday night or Thursday.
The United States could launch its own intervention in Syria, with the United Nations Security Council unlikely to agree on a mandated intervention, because permanent member Russia - an ally of Syria - is likely to veto it.
Labour foreign affairs spokesman Phil Goff wants Mr Key to share what information he has with parliament and the public - and to call a debate on New Zealand's planned response.
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Mr Goff says the situation in Syria, where the government is believed to have used chemical weapons on its citizens, killing more than 350, cannot be ignored.
However, he says collective action backed by the UN is the best response, rather than a US-led military strike.
"The first step by the [UN Security Council] should be to stop all countries providing the arms and financial support that feeds the ongoing conflict. New Zealand should be outspoken in seeking that agreement," Mr Goff said.
"We also need to learn the lessons of the past. Ten years after the military invasion of Iraq, over 1000 Iraqi people are still being killed each month in that country.
"The goal must be collective resolve and commitment to stop the conflict, secure the chemical weapons and plan for transition to a new government."
Mr Key on Wednesday said New Zealand's preference was for the UN Security Council "to send the strongest message it can" to Syria.
He is not yet committing New Zealand troops to any intervention.
