H1B employer threatening

Hi I am on H1B through one consultancy. My Employer has given me offer letter stating that I would be working on in-house project. But once I arrived, I was put in sub-contract. Now I left that company and got full time job. Employer is threatening for liquidity damage. But I think, I signed that contract only considering the in-house project. This is clear case of cheating. I need your comment from you. Can I file case against my employer on DOL

Get a lawyer. Labor laws are different per-state and too complex to answer without all the details. Keep records of all emails, phone conversations etc.