The veteran director was repeatedly linked to the job, but Radcliffe has described the reports as "absolute rubbish".
Speaking at the BAFTA ceremony in London yesterday, he told Heart radio: "I have no idea how that rumour started or where it came from. It's not true. How's that for a definitive answer?
"It's absolute rubbish that Spielberg is directing the final film. It's not true. There's absolutely no foundation in that at all."
On the subject of the sixth movie, Harry Potter and the Half-Blood Prince, he added: "We're getting through it alright. I'm really enjoying it. We're about six months in and we've only got four more to go."