iAugment, a breast-implant simulator, allows users to take photos of their chest, enhance their bust to different cup sizes, find a recommended surgeon and publish the photos on Facebook to get others' opinions.
Women's advocate Melinda Tankard Reist has slammed the app, saying it is inappropriate and wrong.
"We have a huge problem in this country with body image and anxiety and are seeing this being expressed in younger girls every day," the Daily Telegraph quoted her as saying.
"A simulator like this plays into that by normalising breast enhancement... This app is just priming and preparing girls for future surgeries.
"Rather than helping them accept their natural bodies, it makes them feel from an early age that there is something wrong with them," she said.
The iLust app is another one with a 12+ maturity rating. Complete with timer and 'ogle meter', the free-to-download app shows youths how to 'sneak a peek at a hottie without getting caught'.
"The app is just teaching boys tips for sexual harassment," Tankard said.
"Apple is entrenching, embedding and spreading sexual harassment and this app shows how little corporate social responsibility there is," she added.
Apple's rating system states that applications in 12+ or less category may contain infrequent mild language, fantasy or realistic violence, mild suggestive themes and simulated gambling that may not be suitable for children under age 12.
Australian Family Association spokeswoman Terri Kelleher said the apps were inappropriate for children and should be blocked.
"Children are naturally curious. They may come across these apps by chance and not have the cognitive ability to understand the implications of what they're seeing," she said.