The country's postal service this week released a series of five stamps depicting "Memin Pinguin," a child's character from a comic book started in the 1945 that is still published in Mexico.
In Washington, the White House objected, saying that "racial stereotypes are offensive no matter what their origin." The Rev. Jesse Jackson branded the stamp "an insult" and asked Mexico to withdraw it from the market.
Withdrawing the stamps would probably make them more desirable to collectors and increase their value, say U.S. collectors.
But Ruben Aguilar, a spokesman for President Vicente Fox, said the comic book has promoted understanding and family values for decades and deserved to be enshrined on a stamp.
"It seems strange to me that this celebration of Mexican culture and Mexico's post office's toast to Mexican cartoonists is misunderstood," he said.