The ad, by the Saatchi & Saatchi agency in New York, depicts an apparently biracial child asking her white mother about the benefits of Cheerios, saying her dad had said "Cheerios was good for your heart." The ad ends with the girl's father, a black man, waking from a nap to find a pile of Cheerios covering the left side of his chest.
The advertising trade publication Adweek reported the online backlash against the ad included comments referring to "Nazis, 'troglodytes' and 'racial genocide.'" The YouTube comment section for the ad has been disabled.
The flame war was noted on the social media site Reddit and the YouTube video of the ad had more than 900,000 views as of Saturday.
Journalist Mary C. Curtis, writing in the Washington Post Friday, called the flare-up "more proof, if anyone needed it, that the post-racial American society some hoped the election of an African-American president signified is far from here."
Curtis, who is African-American, said the ad resembles the breakfast ritual at her house, where she has a son with her white husband.
"The point is, it's no big deal," she said.
"In making this ad, Cheerios is just reflecting the new reality, and might be gaining themselves many more customers than those inclined to punish them -- if those folks even ate the cereal to begin with," Curtis said.
A commenter on Cheerios Facebook page praised the ad and criticized "hateful people [who] are in such a frenzy over what is a modern family structure."
Cheerios spokeswoman Camille Gibson told the website Gawker her company knows "there are many kinds of families and we celebrate them all."