"We had no helicopter. We don't use that," he said. He described the incident as "just the creative imagination of this Tulfo."
Duterte did not clarify who Tulfo was, but he could have been referring to a number of journalists with the same surname.
• suggested he would end an agreement allowing a US military presence in his country
• said he would continue his controversial fight against drugs "until the last drug lord is killed."
'I did that before and I can do that again'
In a televised speech Tuesday, Duterte said he had previously thrown someone off a helicopter and threatened the same fate to anyone misusing public funds.
"Whoever will use this (public funds) for corruption, I will get him (to) ride the helicopter with me going to Manila and will push him out while we we are up in the air," Duterte said. "Yes I will do that! I did that before and I can do that again."
When asked if the event actually happened -- and if the person killed was a kidnapper, as local media was reporting -- Martin Andanar, the presidential communications secretary, told CNN: "It happened; he said it."
Duterte: 'I am playing you'
"I am playing you, I am really like that, your team knows I really want to say jokes. When I say for example, when I pray ... like what God told me ... it is the same. And you spent time writing about it, criticizing, and that is your story, and you believe that."
Strained relations
Asked by CNN Philippines if he is expecting a different relationship with President-elect Donald Trump, Duterte said: "Yes ... I am really waiting because that person is kind ... like in a street language, he is easy to get along with. Like when I say to him, 'You know we have the same mouth Mr. President, you know, the only problem is that yours in English, mine in my dialect but same.'"
Duterte told CNN Philippines: "Why won't I kick them out? They want to destroy me. Who will be a stupid person, a President that will allow that? If you are here for your own benefit, no need to do maneuvers with the Filipino soldiers, they are good, better than you.
"It is only on your own convenience, on your own pacing. You are just bullying China. If you really want to recover the whole South China Sea, go and start it now. Go and send all your ships and battle and all."
Before Duterte's rise to power, the Philippines was expected to be a key US ally in defending the maritime rights of a number of Southeast Asian nations embroiled in a long-running dispute with China.
Drugs crackdown
Duterte was elected to office in May on a platform of cracking down on crime, particularly illegal drugs.
Asked by CNN Philippines if this fight was over, Duterte said it would continue "until the last pusher is out of the street.
"And I should be very frank with you and the country," he said, looking directly into the camera. "Until the last drug lord is killed," he said, swiping his hand across his throat, "this campaign will continue to the very last day of my term."
CNN's Pamela Boykoff and journalist Jinky Jorgio reported from Manila and Laura Smith-Spark wrote from London.