He was wrong.
Wrong or right, I doubt that any of our presidents has never referred to the U.S. as a democracy.
“The American Dream is freedom, prosperity, peace-and liberty and justice for all. That’s a big dream. It’s not always easy to achieve, but that’s the ideal. More than any country in history we’ve made gains toward a democracy that is enviable throughout the world. Dreams require perseverance if they are to be realized, and fortunately we’re a hard-working country and people. We are the luckiest people in history, just by the fact that we are Americans.”—Donald Trump
https://www.azquotes.com/author/14823-Donald_Trump/tag/democracy