A strike from substitute Rob Earnshaw was enough for Forest to do the double over their neighbours, with the beaten hosts having Dean Moxey sent off late on.
Forest stand sixth in the table, four points behind second-placed Cardiff but with two games in hand on the Bluebirds, and games in hand over each of the other teams above them.
"It's another very important away victory against a very good side. They were obviously up for the game and you could feel the energy before the match," said Davies. "I thought we played with very good discipline in the first half and we should have been two or three goals up but we showed a lack of composure and quality with the final ball."
The Scot added: "I still think we need more bodies in the club to keep the competition high and cope with what will be a tough, tough ask over the next few months," Davies said.
"This is not a time to get carried away, the players will be back in tomorrow (Sunday) and there are a lot of twists and turns to come."