The 53-year-old model, who also has her own perfume and skin care products, said the first lady should get better with age instead of struggling with her looks as most women of "great beauty" do, Parade magazine reported online Friday.
"Mrs. Obama is not a great beauty," Iman told the publication. "But she is so interesting looking and so bright. That will always take you farther. When you're a great beauty, it's always downhill for you. If you're someone like Mrs. Obama, you just get better with age."
While Michelle Obama is the first black first lady, Iman was among the first black supermodels. The Somalia-born model told Parade magazine breaking through that fashion barrier was difficult for her.
"I did feel a bit ostracized," she said. "You suddenly represent a whole race, and that race goes, 'Well, that person does not represent our ideals of beauty.'"