In the “U Smile” video, Justin Bieber and Anastasia Kassar have incredible chemistry and he sings about her lips — so why doesn’t he seal the deal with a kiss? HollywoodLife.com has the exclusive behind-the-scenes answer!

Justin Bieber is quite the charmer in his “U Smile” video! The 16-year-old pop star meets a beautiful blond fan, played by actress Anastasia Kassar, and is taken by her lovely smile. However, despite singing about her lips (his “biggest weakness”), Justin never actually puckers up — and Colin Tilley explained to HollywoodLife.com why Justin passed up the chance to get up close and really personal with his stunning co-star!

“We try and keep it PG,” the 22-year-old director told us exclusively.

After going though tons of head shots and resumes, Colin says something about Anastasia stood out, which is why she was  the perfect fit to play Justin’s love interest.

“She just seemed like she really worked for the party and the tone of the video and song. She had a great personality and that really helps when you’re on set.”

In fact, Justin and Anastasia hit it off so well, they ended up improvising most of their flirty interactions in the video (we wonder how his GF feels about that!)!

“On set, I’d say 75% of our stuff…is improv from Justin, just a lot of the natural moments with [Anastasia],” Colin explained. “Some of the stuff in the hallways, with them running down, on the pole and stuff — that was just in the moment. And that whole intro part was actually freestyle. Some of the raw footage was from a flip cam. We made it work!”

They certainly did. Justin and Anastasia’s natural chemistry is undeniable, but even with sparks flying on set, it hasn’t steered Justin away from his girlfriend Jasmine Villegas who joined Justin on his recent Hawaiian vacation with The Karate Kid star Jaden Smith. We gotta admit, we’re secretly bummed they kept the video PG — we wanted to see a kiss!

–Kirstin Benson, reporting by Sarah Rose Attman

Justin Bieber‘s music video for “U Smile” came out today, Oct. 1, and the buzz around Hollywood isn’t just about our beloved Bieber. Everyone has been wondering who the video’s leading lady is and here’s what HollywoodLife.com knows!

Anastasia Kassar is the lucky girl to snag the dream role as the fan Justin falls for and it turns out Anastasia is a true talent in her own right. We found out Anastasia is a singer/songwriter, actress and athlete. She speaks French, plays piano, models and knows six styles of dance! If that’s not enough to prompt jaw dropping and make J’s gf, Jasmine Villegas nervous, Anastasia tweeted a sweet thank you to Justin after they wrapped filming.

“@justinbieber,Working with you was a dream come true! I am sure all of your fans will love the video! Thank you for everything! :)”

Let’s not forget that Justin’s current real life love interest, Jasmine, was the leading lady in his “Baby” video. Oh and then there was Kristen Rodeheaver who he personally picked for his “One Time” video and briefly dated. Uh oh, Jasmine you better watch out! Your leading lady days may be numbered!

Kirstin Benson, Aimee Curran, Nicole Fukuoka & Sarah Rose Attman

1. Did Justin Bieber Find Love at a Romantic Wedding?
2. VOTE! Is Justin Bieber’s New Video ‘U Smile’ His Best Ever?
3. Lamar Surprises Khloe With An Anniversary Dinner
4. Lady Gaga Flashes Her Bum to Thousands of Fans