Is it permissible to make Salaam to a person that is busy reciting the Quraan Sharif or partaking of meals?
It is Makrooh to make Salaam to a person that is engaged in the recitation of the Quraan Sharif or partaking of meals. If someone makes Salaam at such an occasion then replying to such a Salaam is not Waajib. Similarly, it is not Waajib to reply to a person that greets whilst the Adhaan is being called, as reply to the Adhaan is Zikr and replying to someone whilst engaged in Zikrullah is not Waajib.
Re:- Fataawa Mahmoodiyya pg.31 vol.28