Answer: It appears to me that if someone is compelled to discharge the Zakaatul-Fitr by money, then he should give them the money, and not openly disobey those in authority. But, as far as that which is between him and Allaah, he should discharge what he has been commanded by the Prophet (sal-Allaahu `alayhe wa sallam) to discharge. So, he should discharge a saa’ of food as the Prophet (sal-Allaahu `alayhe wa sallam) commanded. Their compelling you to discharge it from money is compulsion to do something which Allaah has not legislated. In that case, you must fulfill what you believe to be obligatory.
Shaykh Ibn ‘Uthaymeen fatwaonline.com