President Obama's exclusive sit-down interview with David Muir will air Monday on "World News Tonight with David Muir" at 6:30 p.m. ET and on "Nightline" at 12:35 a.m.
Obama said while he didn't want to comment directly on Trump's comments, the American people should expect better from leaders running for the nation's highest office.
"The point is, is that our democracy works not just because of the laws we have in place, but also the norms and customs that we've maintained," Obama said. "There is an expectation that our leaders will not trumpet violence or justify it."
Obama has said repeatedly that he does not believe the American people will elect Trump to the presidency.
Trump has said on a number of occasions that he does not condone violence, but said that he may not be able to control the situation.
“I think we’ll win before getting to the convention but I can tell you if we didn’t and If we're 20 votes short or if we’re 100 short and we’re at 1,100 and someone else is at 500 or 400 cause we’re way ahead of everybody...I think you’d have riots,” Trump said on CNN last week.