The 18-year-old singer, who has been dating the former Disney star for two years now, said he was a little nervous beforehand, reported Contactmusic.
"My first kiss with Selena was magical even though I was a little nervous beforehand. It was in the car. It was scary and spontaneous and it was just awesome," he said.
The 'Baby' hitmaker said he does not want to show-off his love for Gomez and wants to enjoy the feeling of being in it.
"What does love feel like? It feels good. If you're really in love then you should get butterflies. Butterflies and happiness, that's how I feel anyway.
"But I never like to throw it in my fans' faces. I love my fans and I'd never want to do that to them. It's my private life and I like to keep separate. I don't have many things that I get to keep to myself but that's one thing and I don't want to rub the relationship in the faces of his millions of female fans."