Lions fly-half Jonathan Sexton grabbed one of three tries, as well as kicking eight points from the tee, to ensure Ireland got the summer off to a winning start.
Fellow Lions Simon Zebo and Conor Murray were also involved in the 29-17 victory but O'Connell, who captained the 2009 tour of South Africa, was not content with the performance.
"They put us under a lot of pressure, I think the result is great but the performance is disappointing," he said.
"We didn't know we were going to be as inaccurate as we were. We put a lot of balls down and missed some tackles.
"They had some very big men, some really good footwork and they put us under a lot of pressure and it kind of thrived off our mistakes, we were unlucky not to score a try early in the first-half. And 30 seconds later we were lucky not to concede a try.
"So that's kind of the way they play and we knew that but I suppose we were intent on trying to stop that and we didn't do that."