Salary deduction and the procedure of disciplinary actions

Recently, there was a change in the management of our company and my new manager didn't like the way I look. He told me about it and warned me that next time I will be fined.

After a week or so, I received a notice that I'm fined of AED 500 for the unprofessional appearance.

I work for the company for a long time and I've never had such a kind of complaints before. I believe that my appearance is appropriate.

Moreover, there is no strict dress code in our company and I've never seen and never signed any papers in this regard.

Does my manager have the right to decide how I look? Is this penalty legal? Do they have the right to deduct it from my salary?