My Pep, also a Maine Coon, can bite hard when he's over stimulated. We generally just stop playing with him (which is fine with him, he's kind of an ornery 18-year old). But I can understand your kitty not understanding and still wanting to play.

You may already know this- but when cats bite and break the skin, it can be real hazardous to humans. Vivi bit my husband a few years back while she was playing and broke the skin, and he developed a severe infection and nearly lost his hand. Be sure to wash any bites that break the skin and seek IMMEDIATE medical treatment if they start to turn red or swell.