In an email received Thursday, Mike Siemienas, a General Mills spokesman, said the “online communities” mentioned in the policy referred only to those online communities hosted by the company on its own websites. He later elaborated in a second email: “No one is precluded from suing us merely by purchasing our products at the store or liking one of our brand Facebook pages. For example, should an individual subscribe to one of our publications or download coupons, these terms would apply. But even then, the policy would not and does not preclude a consumer from pursuing a claim. It merely determines a forum for pursuing a claim. And arbitration is a straightforward and efficient way to resolve such disputes.”

Image General Mills makes Pillsbury items. The company said its Facebook and Twitter accounts were not part of its new policies. Credit... Scott Olson/Getty Images

But if General Mills offers a consumer a coupon in exchange for “liking” one of its brands on Facebook, she will still have to agree to the new terms to get it, Mr. Siemienas said.

Lawyers had pointed out that the new terms were vaguely written, leaving them open to a wide range of interpretation. A pop-up notice on the company’s home page, for example, says that the new terms “require all disputes related to the purchase or use of any General Mills product or service to be resolved through binding arbitration.”

“It is very clear that if you do any number of things, you are covered by these changes,” said Julia Duncan, director of federal programs at the American Association for Justice, a trade group for trial lawyers. “If you use a coupon, go on their website, participate in a promotional campaign of any sort, sign up for email alerts or ‘participate in any offering by General Mills.’ That is so exceptionally broad that it may be possible anything you purchase from them would be held to this clause.”

News of the changes attracted interest on social media, where legal experts debated the enforceability of the company’s policy and consumers expressed a variety of opinions. “I’m not going to like this page. I do not agree to arbitration ...,” one visitor to the Cheerios Facebook page wrote.