It is not a matter of Halal-Haram, but rather a matter of etiquettes. Before commenting on such matters, we need to first study the whole incident as to its how, where, when and why. In the absence of complete information, it is not appropriate to give a blanket statement in this regard.
A few principles should be kept in mind though:
– There is no absolute prohibition of music or beating pots in Islam. Many scholars give sermons in a melodious voice in different mosques across the Pakistan. Also there is no prohibition of reciting Naats in a mosque.
– The custodianship of mosques in Islam is given in the hands of the state. Because of non-application of this principle, many such objectionable incidents happen. Mosques do have a certain sanctity that need to be observed and states can ensure that provided they have administrative control of the mosques.
– If it was a sermon of Friday, then as per established Sunnah of the Prophet, there are two sermons of Juma; the first one is for reminder (tazkeer-o-Nasihat) and the second one is for praise of Allah (hamd-o-sana) and for Prayers (‘dua‘).
– If some Imam is seen violating any of above requiements and has shown non-seriousness in this regard, then he should be advised in a civil manner to be more careful in fulfilling the reqirements of the sermon and that he should also be respectful to the emotional sensitivities of the Muslims.