Tess Holliday, a plus-size model known for her '#effyourbeautystandards' campaign on social media, tweeted her disproval.
"How did this get approved by an entire marketing team? Why is it okay to tell young kids being fat = ugly?" she wrote, tagging Chloe Grace Moretz at the end, who reportedly voices Snow White.
One commentator branded the poster "awful", while another person said it should deter viewers from going to see the film. "This is some major BS-the majority of American women who are that size shouldn't take their kids or buy anything related to that project," the woman tweeted.
Another wrote: "Wow!! What a way to tell my daughter that you have to be thin to be beautiful! Her momma is curvy and beautiful!"
The website for Lotus films suggests the film has a message of empowerment, explaining that the character is on a journey to find her lost father and learns "not only to accept herself, but to celebrate who she is, inside and out."
The character, according to producers, learns: "to let the beauty within ... shine brighter than anyone else in the land."
The film is due to be released next year.