Daniel Powell and Patrick Bamford scored the goals for the visitors which leaves the U's five points above the bottom four with two games remaining.
Dunne said: "I thought we were great and I was delighted with our overall effort and commitment. We didn't deserve to lose 2-0 and the difference between the two sides was a bit of quality.
"The quality of the likes of Bamford and (Luke) Chadwick was there to see and that's why they're near the top of the league.
"But you can't fault our commitment and we had players coming off with cramp and they've given their all.
"I thought we dominated in the first half but switched off for a moment and these things happen. We hit the post and we've had scrambles and shots on goal.
"We hit the side-netting and had good deliveries into the box.
"It was just that final ball and on another day we'd beat another team by four or five goals.
"I'm really proud and I can't wait for Saturday (against Shrewsbury)."