Martinez paid tribute to both sides for an absorbing encounter, but admitted defensive sloppiness had cost his side the victory as Everton continued to push forward in search of a second-half equaliser.
Martinez said: "We started better in the first half and Everton came back and had a strong second half as you would expect.
"They played with real tempo and intensity and they are a group of players with very good momentum.
"But we're the home side and I'd say we should have defended better to get the three points.
"My only disappointment is that the first goal is too soft. We need to learn to defend better in terms of concentration and intensity. But I'm pleased with the performance.
"The link-up play between the front three was a joy to watch and we scored two goals with great pieces of football. But we needed that two-goal cushion - and we needed to do other things better to take the points."