The actress was asked to pose in a seductive manner by the director, according to sources.
An insider told Mid Day: "Since it was a soap ad, Katrina was required to shoot for her scenes inside a bath tub. Despite giving several shots, the director didn't think Kat was emoting the right 'seductive' expressions.
"He requested her to try once more. Kat was cordial with everyone on the sets. However, after the director made his request, Kat lost it."
Kaif will also be appearing in an action sequence in an advertisement for paint, based on a stunt in Ek Tha Tiger.
The action film, also starring Salman Khan, broke all opening day box office records on its release in August.
Watch the video for the song 'Mashallah' from Ek Tha Tiger below: