Darren Randolph's fine performance saved Ireland on Thursday, as the goalkeeper pulled off a string of quality stops to help the hosts avoid a humbling defeat.
Northern Ireland would have been worthy winners, with O'Neill's switch to a 3-5-2 system doing little to improve Ireland's attacking play.
Boos from the home crowd were audible at full-time, and O'Neill believed that the criticism was justified, with Ireland having won just one of their past 10 international matches.
"We're in a results business and we need to improve," O'Neill told Sky Sports when asked if his job was under scrutiny.
"We made a few mistakes that could have cost us in the end. Randolph made some really good saves. Overall, we didn't do enough.
"We didn't do enough, certainly going forward. Now we've stopped leaking goals we have to improve going forward.
"We're in a transitional period at the minute, we might have some of our more experienced players coming back, so I think we're in a good position to turn it around."
Northern Ireland boss Michael O'Neill, meanwhile, could find little fault with his side's display despite their wasteful finishing.
"I'm proud of how the team played, we were very dominant in the game, had our chances but didn't take them, and Darren Randolph had a great game," he told Sky Sports.
"We deserved to win the game, I'm really pleased with the performance.
"We've got two young players in Gavin [Whyte] and Jordan [Jones], and both would normally take those chances, so they're disappointed, but they're both good players.
"The gameplan was to come and control the game and I think we did that. At no point in the game did I feel we were not in control.
"Possibly we could have created more chances than we did. We have to be more clinical in our final pass, it's an individual thing.
"We have to get the players in those areas and take it up a level, hopefully that'll come with more experience and starting to win games again and get that momentum."
While Ireland's Nations League fate could be determined before they take on Denmark on Monday, Northern Ireland have already been relegated from League B thanks to Austria's draw with Bosnia-Herzegovina.