"Who is really fighting for a noble cause in Syria? There's so many people fighting for different personal gains and different political gains, that you don't really know who you're fighting with anymore."
Meanwhile, Ali Akil of Syrian Solidarity New Zealand, revealed that two brothers had been prevented from leaving New Zealand as they tried to make their way to Syria.
"According to my sources, their parents are the ones who called up and asked for them to be stopped," he said, accusing Mr Key of "scaremongering and providing twisted information for political gain".
The brothers were the only people he had heard of who had attempted to join the rebel forces, he said.
"John Key has suggested very few people have [gone to Syria], and mentioned they have gone there to fight against the Assad regime which is actually something that we should honour them for, not strip them of their rights for," he told Morning Report.
He questioned why Mr Key would "criminalise" those who decide to fight against Bashar al-Assad's regime, which is known to have used chemical weapons against civilians.
"The New Zealand Government has actually sent our own New Zealand soldiers to Iraq and Afghanistan to liberate them from dictators, or so we were told. Isn't it ridiculous to now criminalise those who choose to do exactly the same thing in Syria?"
He added: "New Zealanders have been taking part in conflicts around the world, including those who have joined Israeli forces, yet we have not heard of their passports being cancelled."
Mr Akil said such actions by the Government would be more likely to radicalise young, disillusioned Kiwis than fighting in Syria.
"I think what radicalises people is injustice, and that's exactly what John Key has done in this case. It's stripping people of their rights."