Can a person who is performing ablution be greeted with salam?

Salam (greeting of peace) is one of the practices highly emphasized in our religion. The Prophet Muhammad (peace be upon him) stated that exchanging salam would lead to the spread of love among Muslims. (Muslim, Iman, 93 [54]) However, it is not appropriate to greet people with salam if they are in a situation where they cannot respond. For example, it is considered undesirable (makruh) to greet someone who is reciting the adhan, reading the Qur'an, delivering or listening to a sermon (khutbah). Since ablution (wudu) is both a preparation for worship and, in a sense, an act of worship itself, it is more appropriate not to greet someone who is occupied with performing ablution.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu