Read more on US Presidential elections 2016
"On Wednesday night, Donald Trump did something no other presidential nominee has ever done. He refused to say that he would respect the results of this election. By doing that, he is threatening our democracy," Clinton said at an election rally in Ohio.
Clinton's remarks were followed by two round of booing by the audience against Trump, who during the third and final presidential debate in Las Vegas on Wednesday said that he can't commit at this point if he will accept the results of the presidential elections.
"He (Trump) is basically saying hey, we have been around 240 years and we have always had peaceful transitions no matter who won or who lost. Look, if you lose an election -- I have lost elections, you don't feel very good the next day, do you? But we know in our country the difference between leadership and dictatorship, right?" Clinton said.
"The peaceful transition of power is one of the things that sets us apart. It is how we hold our country together no matter who is in charge. I went to 112 countries as your secretary of state and I saw the difference between what we do and what others do, I was in countries where people jail their political opponents or execute them or exile them or invalidate elections that they didn't win," she said.
"That can never be allowed to happen here. I believe that's true no matter who you support in this election, whether or not you support me. Or you support my opponent, together, we must support American democracy and the country that has given every one of us so many opportunities," she said while urging her supporters to come out and vote.
Clinton also slammed the economic policies of Trump alleging that he plans to give tax cuts to the wealthy. "He really believes if you give trillions, that's with a T, trillions in tax cuts to the wealthy, to millionaires and billionaires and corporations, everything will work out."
"It's really trickle down on steroids. I believe differently that we must invest in working families in the middle class, in small businesses, that will boost the economy," the Democratic presidential nominee said.