The double-page magazine ad showed an image that appeared to have been shot through a slightly open doorway revealing a young woman wearing Miu Miu clothes and reclining on a bed.
The Advertising Standards Authority received one complaint that the ad showed a child dressed in a sexually suggestive pose.
The ad featured Mia Goth, a 22-year-old actress and model. Vogue UK said the magazine was sophisticated and did not believe their readers would think the ad made any suggestion the model was a child.
PradaSpa, the owner of the Miu Miu brand, refuted the complaint and said the ad was part of a campaign featuring three different models in a series of "cinematic tableaux".
But the ASA said the ad’s "crumpled sheets and her partially opened mouth" also enhanced the impression that her pose was sexually suggestive.
The watchdog said: "We considered that her youthful appearance, in conjunction with the setting and pose, could give the impression that the ad presented a child in a sexualised way.
"Therefore we concluded that the ad was irresponsible and was likely to cause serious offence."
The ad must not appear again in its current form and the ASA told PradaSpa to ensure future ads did not include images that inappropriately sexualised young women.