The ‘Kill Bill’ star was caught on camera locking lips with entrepreneur Lapo Elkann at the amfAR auction held during the bash in the South of France on Thursday.
But the 46-year-old actress, who was hosting the annual charity event, has since blasted the former CEO of Fiat cars, accusing him of ‘opportunism’, adding that she wasn’t ‘complicit’ in the surprise kiss.
The rep added to E! News: "It looks like she was happy to have it happen, but it was not consensual."
The 38-year-old businessman kissed the actress after bidding $196,000 to win a Victoria's Secret Fashion Show experience.
He also donated his Ferrari 458 Camouflage in order to raise money for AIDS research.
Other stars who attended the gala included Katy Perry, Orlando Bloom, Dame Helen Mirren, Kirsten Dunst, Rosie Huntington-Whiteley, Alessandra Ambrosio, Jourdan Dunn, Adriana Lima and Heidi Klum.
Leonardo DiCaprio also gave a speech and auctioned off a week-long stay for 12 people at his Palm Springs home for $500.000.