The Victoria’s Secret model stars in the TV ad promoting the practical collection.
The black and white video shows the 26-year-old playing tennis in a white midriff top and underpants from the line. She asserts herself as a fuss-free tomboy as she prances around on the tennis court hitting balls on her own.
The male voiceover in the video says, "If you're feeling under pressure, these pants will you keep you fresher," and, "never baggy or saggy like grandmother's sweater, p-p-p-p pants!"
The blonde beauty is following in the footsteps of models Elle Macpherson and Gisele Bündchen who have released lingerie lines.
Bar, who dated Leonardo Dicaprio for six years until they split last year, describes the line, under.me, as "a focused collection of beautifully-made basics that look good and feel amazing.”
“I feel I look my best when I'm comfortable. Especially when it comes to underwear,” she said.
"My underwear is the clothing article closest to my body, and as such, I want it to complement it and not steal the show.
"There is nothing better than simple, comfortable, quality clothing."
The Israeli-born star has previously described her look as casual.
“I'm pretty easy with hair and make-up,” she told Harper’s Bazaar. “I don't like my hair too done and I prefer natural make-up. I would say when your skin looks radiant and glows, and you combine it with a good smile, you can't go wrong.”