"Keine jugendlichen Mädchen sind im Restaurant."

[sue.cortese]

I wasn't sure which was correct so I looked it up in the dictionary and teenage is correct. My spell checker agreed. However, no one says juveniles except for the police.

[duoderSie]

Agree.
It accepts "youthful girls" but since all girls are youthful it's not great english. I have learnt to type such rubbish English in DL because the risk of losing a heart by typing good English is too great

[cephalium]

"Young girls" would be more acceptable English here