The ASA ruled the ad breached its broadcast code and banned it from being shown again in the same format.
“The white skin, depicted as smoother and clean after using the product, was shown successfully changed and resolved,” the ruling said.
“We considered that could be interpreted as suggesting that white skin was superior to black skin.”
The ASA said it accepted that this message was not intentional but warned Colgate-Palmolive to “ensure they avoided causing serious offence on the grounds of race” in future.
Clearcast, which approves or rejects ads for broadcast on television, said the advert did not perpetuate negative racial stereotypes.
One model with darker skin was depicted in a “stylised and unrealistic way” to demonstrate dryness, but their skin tone was otherwise not a focal point, the agency said.
A second model, also with darker skin, was shown with itchy skin, but this was portrayed through scratching visibly healthy skin and the resulting marks, and was therefore more about sensation than any visible skin condition, it added.
Sanex told BBC News: “We take note of the ASA Council’s ruling. Our advert was intended to highlight how our Skin Therapy range supports healthy skin across a variety of skin types.
“At Sanex, our mission is to champion skin health for all, which is portrayed across our brand communications.”