Paltrow and Downey Jr. discussed their on-screen smooch at a recent Los Angeles news conference promoting the action picture.
"I couldn't get her off of me. It was embarrassing," Downey Jr. joked with reporters.
"It was great because both my husband and his wife (producer Susan Downey) were right there," Paltrow clarified.
"She said to me that I didn't know what I was doing. Like it didn't feel good," Downey Jr. recalled. "And I'm like, you know what? First of all, we're all friends, so what would be creepy is if I was coming off all sexy to you while we're, by the way, I've done that in movies and it creeps them out. So why am I going to creep you out? What am I? ... Despite what she said on set, she still thinks about it."
"Iron Man 2" is set to open in U.S. theaters Friday.
Downey Jr. plays the titular hero, while Paltrow portrays his friend and business partner Pepper Potts.