"We're looking at it very, very seriously. I don't like it at all," Trump said on Fox News.
"I don't like it, I don't like it with respect to reporters," he said. "It's a terrible, terrible precedent, we can't let it happen."
Khashoggi, a dissident and Washington Post columnist, was reportedly lured back to Saudi Arabia and may have been killed.
"And we're being very tough, and we have investigators over there and we're working with Turkey, and frankly we're working with Saudi Arabia," Trump said. "We want to find out what happened. He went in, and it doesn't look like he came out."