Hello mubin and welcome to the UAE job forums
That sounds like a legal question I'm not qualified to answer. I expect you can change your job if you want, the question is more to do with what the consequences will be. I think that it will depend on what you have agreed with the various companies involved. If you have signed a contract with the first new company then if you don't follow through with that, you have broken the terms of your agreement and the company might have a legitimate claim against you for financial compensation. If you haven't signed anything but made a verbal agreement then it will probably be more difficult for the company to make a claim against you.
I would suggest you contact either the UAE Labour Ministry
to see what the official position is on your transfer, and/or a lawyer to see what legal options you have and the possible consequences.