The Arsenal manager fears Wilshere's energy reserves are dangerously low after an arduous season and believes playing the 19-year-old will put him under enormous physical stress.
Coming through: Wilshere is set to represent England at this summer's European U21 championships
Likening Wilshere's energy levels to a car running low on petrol, Wenger said: 'Jack Wilshere is in the red for a while now and this can be a risk for his health. Jack will respect the decision. He knows he is nearly at the end of his energy level but he is keen to do well. He has played nearly 50 games this year. To go to a tournament is a massive risk.
'I am happy if the Under 21s do well because I want England to do very well. I think it is not the right decision but will respect it and let him go.'
Under 21 manager Stuart Pearce yesterday delayed until Monday the announcement of his squad for the tournament in Denmark, but Wenger disclosed Wilshere had been called up.
Pearce wants to make sure those who he is expecting to travel to Denmark all come through Sunday's final round of Barclays Premier League fixtures unscathed.
Jack's the lad: Wilshere has played 52 games for club and country this season
Starlet: The 19-year-old expressed his desire to play in the summer tournament
But the delay has raised a number of questions, not least regarding Liverpool striker Andy Carroll, who has voiced concerns over whether his body will stand up to the demands of tournament football.
Carroll has made only nine appearances since December and looked woefully short of match practice when he returned to Liverpool's starting line-up against Tottenham last Sunday.
Pearce spoke with Wilshere early this spring and told the youngster he would understand if he decided that taking a break this summer would be better.
The conversation, though, left Pearce in no doubt that the enthusiastic Wilshere was up for the challenge of helping lead England out of a group that includes Spain, Ukraine and the Czech Republic.
'He likes playing for the Under 21s,' said Pearce. 'It would be hard for me to turn around to him and say, "Have a rest, son". I won't give leeway to anyone I deem necessary in the 23-man squad.'
Wenger has been particularly outspoken about Wilshere's involvement, while Liverpool manager Kenny Dalglish has also raised concerns and suggested that age-group football is about developing players, not winning tournaments.
One player who has confirmed he did not make the final 23 is Watford goalkeeper Scott Loach, raising the possibility that Fabio Capello will draft him into the senior squad.
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Explore more:People: Fabio Capello, Andy Carroll, Jack Wilshere, Kenny Dalglish, Stuart Pearce Places: Liverpool, Spain, Czech Republic, Denmark, United Kingdom