Everton were on top for periods in the match, especially in the first half, and Martinez maintained an optimistic outlook despite the loss.
Martinez said: "We need to make sure that when we play well, when we deserve to get a positive result for the performance we do that.
"We came here, we showed that we can play eye-to-eye to the league leaders.
"The only disappointment is we couldn't hit the back of the net when we had a couple of good moments of control in the game."
Lacina Traore withdrew after feeling his hamstring in the warm-up, forcing a late change in tactics, with Steven Naismith replacing him.
"It was a blow, but I thought we were lucky it didn't happen in the game," Martinez added.
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