He reportedly burnt his New Zealand passport after going to Syria, and had claimed he had contacted the New Zealand Government to try to get a new one.
Ardern said the Government's ability to help New Zealanders in Syria was "severely limited" because New Zealand had no diplomatic presence in Syria, and its travel advisory was simply not to travel there.
"New Zealanders should not travel to Syria ... if you do we cannot help you return. New Zealand does not have a presence in Syria."
She said Taylor would have to make his way to a New Zealand consulate office to obtain a travel document, and the nearest one was in Turkey.
The Government did not have any contact with those holding Taylor, and she did not know what his living conditions were like.
She would not say if Taylor's family had been in contact with the Government.
While she would not comment on specifics or hypotheticals, Ardern suggested that Taylor would likely be taken into custody under the Terrorism Suppression Act if he returned to New Zealand.
Under the act, anyone who participated in a terrorist group can be jailed for up to 14 years. Participation is defined as enhancing the group's ability to carry out a terrorist act.
Meanwhile, Geopolitical and security analyst Paul Buchanan told Newstalk ZB if he was brought back to New Zealand, an example could be made of Taylor.
"I think the best course of action is to bring him back here, put him on trial and let the world see New Zealand's standards of justice when it comes to returning jihadis," he said.
"If he returns, it would be a good way of demonstrating as this is a cautionary tale for the other wannabe jihadis that are still out there.
"I'm sure [Taylor's] got plenty of harrowing things to say, that might serve as a good deterrent for others."
Taylor told the ABC that he would be surprised if New Zealand did not take him back, though he said it was likely he would have to spend some time in prison.
Ardern said she was confident that New Zealanders would be kept safe if Taylor came back. Although she would not detail the Government's contingency plans, she said it involved police and she was confident police would do the right thing.
"While I cannot talk about specifics of this case, I am confident we have the means to keep New Zealanders safe."
She added that the Government was reluctant to cancel Taylor's citizenship because it would effectively make him stateless, and international conventions obliged New Zealand not to make any person stateless.
There were a "very small number" of New Zealanders who were on the Government's watch list for terrorist reasons, she said.
Eight passports have been torn up since a new law, passed in 2014, came into effect that gave greater powers to the Government to suspend or cancel the passports of those posing a threat to national security.
Those rules were further tightened by the Intelligence and Security Act 2017.
Announcing the 2014 law change, then Prime Minister John Key said that Government agencies had a watch list of between 30 and 40 people "of concern in the foreign fighter context", some of whom had travelled to Syria and remained there.
Taylor, who lived in Australia for 20 years, told the ABC he liked his time with Isis as it had introduced him to a "different way of life". He said he was not a fighter, but a border guard.
He told the ABC he initially taught English but made a propaganda video after he fell under suspicion for being a spy.
"I actually did regret making that video and I know the output was not good for my part but I'll know I'll probably spend time in jail for making that video," he said.
"I was helping to guard a border between Syrian Government ... I had a Kalashnikov," he said.
He only used it for practice, he said.
He was also put in prison by Isis for a "ridiculous reason".
"Because I was accused of drinking alcohol and making alcohol and smoking hashish," he told the ABC.
Taylor's other regret was not being able to afford a slave, he said.
Asked what he would have done with a slave, he told the ABC: "Clean the house, the thing is it depends on the function of the slave. For example, if my wife owned the slave I had no right to the slave whatsoever but if I had ownership of the lady then it basically entitled me to what I wanted her to do as long as it was within Islamic Sharia."
He said he would not force the woman to have sex with him, he said.
But because he couldn't afford a slave, he had to stick with his Syrian wife, he told the ABC.
