Atkinson awarded the Blues a second goal on 49 minutes, despite replays showing that the ball did not cross the line.
The incident has led to renewed calls for goal-line technology. While the Italian believes that technology is a must, he does not think that it was necessary in order to make the correct call on this occasion.
"Everyone knows it wasn't a goal," he said. "I have to be honest, I wasn't 100% sure whether the ball was in or out, because I had two players in front of me. But the feeling was that it wasn't.
"So everyone went to the linesman and asked him. He said, 'It's not my decision, it's the referee's decision'.
"And, of course, as a referee, you have to be 110% sure to give a goal, and of course it wasn't, because the ball wasn't in.
"I'm in favour of technology. I've said so. But on Sunday I don't think it was about the technology. It's about the referee being able to tell whether the ball was in or out."
Cudicini has kept six clean sheets in 11 appearances this season.