I don't think Trump lied about this. As AlwaysThere says, to lie is to deliberately say something you know is untrue.

Trump, amazingly enough, seemed to have turned an off-the-cuff anecdote from a German golfer about brown people submitting ballots into a multi-million priority of his Presidency. A lie is one thing, but setting policy based on lame reasons because of his insecurity seems to be equally as bad. A liar or an insecure naif? No good option here.