The "Iron Man" star's lifestyle company site showed pictures of a little girl wearing one of the two-piece creations designed by her new designer Melissa Odabash, reported Daily Star.
The outfits, which are described as "great for girls who want to look grown up", have sparked outrage among campaigners who claim the images sexualise children.
"We remain very opposed to the sexualisation of children and of childhood. The dangers have been discussed at length, so it is a great pity that such trends continue and that they carry celebrity endorsement," said Claude Knight of Kidscape, a foundation set up to prevent child abuse.