Employer withheld my June salary citing poor performance in Mumbai?

I have been working with my current employer in Mumbai for over a year. Suddenly, they withheld my salary for June, claiming my performance wasn't satisfactory. I was not given any prior warning or performance improvement plan. I'm worried about my financial obligations and feel this is unjust. What are my rights in this situation? Can I legally demand my withheld salary? I feel anxious and don't know what steps to take next.