Oldham travel to Goodison Park for a cup replay on Tuesday evening, with a last-eight home tie against Wigan the prize for the victors.
"As a team we are disappointed because of the kind of goals we lost,' Naismith told evertontv. "It's a real disappointment and I think more so because we probably controlled the game for the first hour. After that Norwich probably went a bit more direct and the two boys up front caused us a few problems.
"We've got a big week ahead of us now. We've just got to put this to one side and put on a professional performance on Tuesday.
"There's a routine the squad follows after games and it will just be a case of getting back on to that. We'll probably talk about the mistakes we've made and try to rectify that for the next game."