The Eredivisie champions begin their campaign in Europe's premier club competition when they visit Camp Nou.
Moisander wants his team-mates to be thoroughly professional on their visit to Barcelona, avoiding a repeat of last season's trip to Real Madrid.
The Amsterdam outfit were beaten 4-1 on that occasion in December, and the Finland international was disappointed when Ajax players were taking photos and videos of the stadium before the match.
Moisander is keen to avoid a similar outcome and told De Telegraaf: "I thought it was a bit awkward last year that before a match against Real Madrid the players were taking pictures and video clips of the Santiago Bernabeu stadium.
"You can't do that. Of course we should be allowed to enjoy the atmosphere but you must not stand there like school kids.
"We must be business-like when we get to Barcelona, do our work properly and try to achieve something.
"We must not show too much respect or play cautiously. If we are scared then we will definitely lose."
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