You can sue, but don't be surprised if you have a harder time finding a job. Unless you have concrete evidence that this is what they said to another source outside the company, and you have evidence that what they are saying is not true you probably do not have a good chance to win this case.
HOWEVER, it might be worth the $$$ to talk to an attorney and have him/her call the previous company to cease this type of communication. Without a lawsuit, sometimes this is the best defense.
Good Luck
