Dallas Mavericks' Shawn Marion Rejects Dancing with the Stars Offer

Sources close to Shawn tell TMZ, "Dancing" sent him an official offer to appear on the show, but the NBA champ wants to make sure he's 100% available in case the lockout ends early ... so it's a no go.

"Dancing" would end in November and NBA season usually starts in October -- which could put Marion in a difficult position if the upcoming season isn't put on ice.