On Saturday, police filed a criminal case against two men in Mumbai for using loudspeakers to recite the early morning azaan and warned workers of Thackeray's party from gathering around mosques.
"Under no circumstances will we allow anyone to create communal tension in the state and the court's order must be respected," said V.N. Patil, a senior Mumbai police official.
A senior official for Thackeray's party said the initiative was not designed to single out Muslims but aimed to reduce "noise pollution" created by all places of worship.
"Our party does not appease the minority community," said Kirtikumar Shinde, adding that police had issued warnings to 20,000 party workers this month.
The issue of calls to prayer extends beyond Maharashtra. BJP politicians in three states asked local police to remove or limit the use of loudspeakers in places of worship.
The deputy chief minister of country's most populous state, Uttar Pradesh, said over 60,000 unauthorised loudspeakers had been removed from mosques and temples.