Experts said that the president's suggestion would likely make the situation more dangerous.
"If you hit that with tons of water from above, that's going to collapse the entire structure and make the situation worse," said Wayne McPartland, a retired New York City Fire Department battalion chief. "If you miss, you might hit civilians in the street."
France made plans to convert six aircraft into air tankers last year, according to the industry website Fire Aviation. Each of the planes can carry 2,600 gallons of water.
By Monday evening local time, France's Ministry of the Interior reported that 400 firefighters were responding to the Notre Dame fire.
At a tax roundtable event later Monday in Minnesota, the president said that the cathedral was "burning at a level that you rarely see a fire burn."
"It might be greater than almost any museum in the world, and it's burning very badly. It looks like it's burning to the ground. So, that puts a damper on what we are about to say, to be honest," Trump said.
The president said that French authorities believed the cause of the fire was the renovation that was underway.
"I hope that's the reason. Renovation, what's that all about? But it's a terrible sight to behold," Trump said.
France's junior interior minister said later Monday that the cause of the fire was not yet known.