Austria won 2-1 with virtually the final kick of the match, as Valentino Lazaro made it four defeats in four for Northern Ireland in UEFA's new competition.
Attention now turns towards next year's Euro 2020 qualifiers as Northern Ireland will hope to forget a dismal Nations League campaign.
O'Neill remarked: "There's a lot more positives than negatives but ultimately we lost the game so that's a negative. In terms of where we are as a team basically we've got to forget the Nations League was ever invented and we're ready to go and play in March."
He also focused on Marko Arnautovic, who made the difference late on in assisting Austria's winner: "He's a top player, a top, top player. When you look at him you see he's a top-four player in the Premier League, he could play in any of the top teams in Europe.
"When you have that physicality, pace, technical ability, it's incredible really. No doubt when you've got a player of that calibre and you drop him into the team he'll give you a special spark and he did that."