Naomi Campbell is Mad at the Cadbury People???

NAOMI CAMPBELL is RAGING again . . . but this time she might have a good reason.  She's thinking about suing the Cadbury candy people, after they ran an ad in U.K. newspapers that compared her to a chocolate bar.

The ad . . . which ran last week . . . shows the new Dairy Milk Bliss candy bar sitting on a pile of diamonds.  And it says, quote, "Move over Naomi . . . there's a new diva in town."

A rep for Cadbury . . . which is owned by Kraft Foods . . . said the ad was meant as, quote, "a light-hearted take on the social pretensions of Cadbury Dairy Milk Bliss."

He added that the campaign was no longer in circulation, and the company has no plans to repeat it.