Malky Mackay said: "I felt the draw was about right. Portsmouth will point to hitting the woodwork and having shots cleared off the line but we also had our chances.
"I felt that having gone ahead with not much longer left that we might have held on to win. We could have been a little more ruthless in those circumstances.
"We knew it would be a strong, physical battle. Portsmouth enjoyed their set-pieces but I think we acquitted ourselves well and got a good draw.
"I've looked at television replays of the shots cleared from the line and in neither case was there a goal."
Steve Cotterill blamed himself for over-working his players in the week leading up to the game.
"We gave a lethargic performance and I have to say it was my fault," he said.
"I trained them too much during the week so all the players are going to get my apologies.
"I have to take responsibility for that performance and for the fact that some of the players had left their legs on the training ground.
"I have to learn from this mistake but there is no doubt that we would have been a yard sharper on any other day.
"There was just not the zip that you would normally expect. Cardiff made two goal-line clearances and I think on another day if the players had not been so tired they might have got to the rebounds first."