The 22-year-old was photographed smoking a cigarette while on holiday in Las Vegas earlier in July, behaviour for which he had already been criticised by the Arsenal manager for a similar incident last season.
Wilshere has returned to pre-season training following England'’s World Cup campaign but did not feature in the Gunners' 2-0 win over Boreham Wood on Saturday afternoon.
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"I know what you can make of pictures. I have to speak to him to see what really happened before coming out publicly.
"I'm not deeply concerned by it but I just want to know what happened but, before I know what happened, I don't want to talk too much about it."
When asked how important the new season is to Wilshere's development, Wenger replied: "Well, he's at an age where you want him to [move] forward. He has the potential.
"I believe for him the most important now is to have a good preparation. Focus on getting really fit.
"Jack is a great player, he has a football brain, he is ambitious. I'm sure, injury-free, he can have a great season."