Los Cafeteros took a 2-0 lead after strikes from James Rodriguez and Juan Fernando Quintero and held out for all three points after Gervinho pulled one back through a solo effort.
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"We didn't deserve defeat," the 42-year-old said in a press conference.
"Colombia took advantage of our mistakes. It was an unfair defeat. Only that."We need to recover quickly. That's it. Let's go back to our quiet training centre and then beat Greece. There is no another alternative."
For the second game in a row Lamouchi chose not to start Didier Drogba, who has scored 65 goals in 103 games for Ivorians, with the striker coming on after 60 minutes - but the coach insists he has no issue with the forward.
"I have no problem with Didier," he continued. "I always do what's best for the team."
Ivory Coast face Greece on June 24 in their final Group C game.