Terminating an employee's contract and asking for medical and visa expenses

I received a termination letter last week, 20th January. I was asked to visit the office. Now, my employer is asking me to pay him visa expenses and insurance expenses (total of 6500AED) since my Emirati ID was issued at the beginning of this month.

I started working for the company restaurant (owned by Emirati) in October. When I visited the HR, she asked me how much I will be able to raise regarding the medical and visa expenses! My response was I can't. I am not able to get the money since I don’t have any source of income.

The HR told me that the owners need their money for the expenses and they will do anything to make sure that they make hard times for me if I don’t pay them, claiming that the owner knows people in the immigration and will report me absconding.

So, because they are holding my passport, I am afraid to go to the police or the labor department because I am just an ex-pat and they are Emiratis and I can not afford to proceed with any legal action against them.