Making a gun gesture with his fingers and shouting “boom”, he told the audience that “if one employee or just one patron had a gun… or if one person in this room had been there with a gun” the attackers would have been stopped in their tracks.
He said: “The terrorists would have fled or been shot and it would have been a whole different story.”
The attacks in November 2015 left 130 people dead after a series of mass shootings and suicide bombings at packed venues including the Bataclan theatre and the Stade de France football stadium.
President Trump reflected on the number of people murdered, and said: “Nobody has guns in Paris, nobody, and we all remember the more than 130 people, plus the tremendous numbers of people that were horribly, horribly wounded.
“They died in a restaurant and various other close-proximity places. They were brutally killed by a small group of terrorists, that had guns.
“They took their time and gunned them down one by one.”
He then simulated lining up and shooting innocent victims, as he said: “Boom, come over here. Boom, come over here. Boom, come over here. Boom.”
He added: “If one employee, or one patron had a gun, or if one person in this room had been there with a gun, aimed at the opposite direction, the terrorists would have fled or been shot.”
People in the audience at the NRA’s annual meeting, held in Dallas, cheered.
Mr Trump added that “if we’re going to outlaw guns” then we are “going to have to outlaw all vans and all trucks, which are now the new form of death for the maniac terrorists”.
The President then turned his attention to London and said there was blood all over a unnamed hospital’s floors, as he referenced the knife murders in the capital this year.
“I recently read a story that in London, which has unbelievably tough gun laws, a once very prestigious hospital right in the middle is like a war zone for horrible stabbing wounds,” he said.
“Yes, that’s right they don’t have guns, they have knives – and instead is blood all over the floors of this hospital.
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“They say it’s as bad as a military war zone hospital. Knives, knives, knives. London hasn’t been used to that, they’re getting used to it, it’s pretty tough.”
The comments come as the President visited Dallas and urged NRA supporters to back Republican candidates in upcoming congressional elections, warning that Democrats would look to tighten gun laws after a series of mass shootings in the US.