The director and cast walked the red carpet at the Mandarin Oriental hotel to promote the film in which Hayek plays the leader of a Mexican drug cartel.
However, things got awkward when Stone seemed mesmerized by the actress' busty figure, and he couldn't resist copping a feel in front of photographers.
Hayek, 46, who is married to French fashion mogul Francois-Henri Pinault, tried to blow off the odd encounter by laughing uncomfortably. Stone, 66, has been married for 15 years.
Hayek's co-stars John Travolta and Benicio del Toro were also present at the premiere.