The GOP presidential front-runner made the comments at the same time that the President addressed a global summit of leaders on climate change in Paris on Monday morning.
Trump was taking Obama to task for his past remarks that global climate change is one of the greatest threats facing the United States and the world.
"I think one of the dumbest statements I've ever heard in politics -- in the history of politics as I know it, which is pretty good, was Obama's statement that our No. 1 problem is global warming," Trump said Monday on MSNBC's "Morning Joe."
The mogul cited the threat of terror and attacks on the U.S. as more concerning.
"I think it's one of the dumbest things I've ever seen, or perhaps most naïve," Trump said. "He actually is somewhat naïve, if you want to know the truth, beyond the incompetent part."
At nearly the same time Monday, Obama was telling world leaders that meeting to reach a global deal on fighting climate change would be beneficial to the fight against terrorism.
"What greater rejection of those who would tear down our world than marshaling our best efforts to save it," Obama said at the COP21 conference, being held in the French capital just weeks after a bloody terrorist attack there.
Obama's secretary of state, John Kerry, who has led the charge both on addressing the civil war and instability in Syria and on climate change, has said that the extreme drought in the war-torn country was a contributing factor to the strife there, which has fed terrorist groups including ISIS. He was clear, though, that it was not the only cause of the war.
The President reiterated that idea Monday, telling world leaders his visit this year to Alaska showed him global warming close up.
"It was a preview of one possible future -- a glimpse of our children's fate if the climate keeps changing faster than our efforts to address it," he said. "Submerged countries. Abandoned cities. Fields that no longer grow. Political disruptions that trigger new conflict, and even more floods of desperate peoples seeking the sanctuary of nations not their own."
Trump said the administration is misguided.
"For (Obama) to say that that's more important than stopping countries like, by the way, North Korea, which is never even mentioned," Trump said, citing their nuclear arsenal.
Asked about his own climate plan, Trump said his buildings have won environmental awards, but his policy amounts to: "I want to make sure we have clean air and clean water."
He also said the U.S. can only do so much when other countries are massive polluters.
"Other countries like China, Vietnam and many others are not behaving," Trump said.
Trump wasn't the only Republican 2016er criticizing Obama's remarks Monday.
New Jersey Gov. Chris Christie criticized the President at a business roundtable in New Hampshire Monday, questioning Obama's belief that "climate change is the American imperative for leadership."
"Say what you want about the nearly now 250,000 Syrians that have been murdered by their own government," Christie said. "I can guarantee you this, they aren't worrying about climate change anymore, if they ever were."
Christie went on to condemn Obama's travels to Paris Monday as "insulting."
"It's insulting, to the position that he holds, it's insulting even more to the responsibilities that are his, for him to be talking about this stuff right now. Rather than trying to unite the world against ISIS, rather than trying to find a solution in Syria, rather than worrying about how we protect the homeland in a way that's effective, he's talking about this other stuff."
Mike Huckabee called Obama out on social media for his decision to focus his efforts on the summit in Paris.
"Obama is clueless. We need a commander-in-chief NOT a meteorologist-in-chief," Huckabee tweeted.