The GOP nominee made his comment at a rally in North Carolina.
Ronald Reagan's daughter has slammed Donald Trump for inciting violence against Hillary Clinton, 35 years after a gunman tried to assassinate her father.
Patti Davis, 63, took to Facebook to hit back at comments that Republican nominee Trump said about stopping Ms Clinton from making Supreme Court appointments.
"If she gets to pick her judges, nothing you can do, folks. Although the second amendment people, maybe there is," he said at a rally in Delaware.
The second amendment in the US relates to the right to bear arms and most viewed his comments as inciting violence, something Trump denies.
To Donald Trump: I am the daughter of a man who was shot by someone who got his inspiration from a movie, someone who...
However, Ms Davis said the true meaning of Trump's comments were "heard around the world."
If she gets to pick her judges, nothing you can do, folks. Although the second amendment people, maybe there is," he said at a rally in Delaware.
"I am the daughter of a man who was shot by someone who got his inspiration from a movie, someone who believed if he killed the President the actress from that movie would notice him," she wrote. "Your glib and horrifying comment about 'Second Amendment people' was heard around the world. It was heard by sane and decent people who shudder at your fondness for verbal violence. It was heard by your supporters, many of whom gleefully and angrily yell, "Lock her up!" at your rallies. It was heard by the person sitting alone in a room, locked in his own dark fantasies, who sees unbridled violence as a way to make his mark in the world, and is just looking for ideas.
"Yes, Mr. Trump, words matter. But then you know that, which makes this all even more horrifying," she wrote.
Officers with guns drawn rush towards assassin John Hinckley after he fired his weapon hitting President Ronald Reagan, Officer Thomas Delahanty, and Secret Service Agent Tim McCarthy outside a Washington hotel. Photo / AP
On March 30, 1981, only 69 days into the new administration, Reagan, his press secretary James Brady, Washington police officer Thomas Delahanty, and Secret Service agent Tim McCarthy were struck by gunfire from would-be assassin John Hinckley Jr., outside the Washington Hilton Hotel.
Although he was "close to death" upon arrival at George Washington University Hospital, Reagan was stabilised in the emergency room, then underwent emergency exploratory surgery.
He recovered and was released from the hospital on April 11, becoming the first serving US President to survive being shot in an assassination attempt.
James Brady was left permanently disabled due to a gunshot wound to the head and when he died in 2014, 33 years after the shooting the coroner ruled it a homicide caused by the gunshot wound he received all those years ago.
