The messaging application also allows a group chat with more than 10,000 members without providing details, including phone numbers, to the group's administrator, a feature that Tito said would be useful for terrorists.
It said "this blocking must be done" because many channels in the service are used to recruit Indonesians into armed groups and to spread hate and methods for carrying out attacks including bomb making.
Web versions of encrypted-messaging app Telegram has been blocked by the Indonesian government and the service could be completely banned, the Ministry of Communications and Information Technology said Friday evening, according to the Associated Press.
He was responding to questions about the Indonesian government's decision to block all access to Telegram, following revelations that several forums hosted on the application were "full of radical and terrorist propaganda".
"Telegram is heavily-encrypted and privacy-oriented, but we're no friends of terrorists", he said.
Indonesians are among the world's biggest users of social media.
Experts fear the southern Philippines could become a new base for the ISIL, including Indonesian and Malaysian fighters returning from the Middle East, as an global coalition retakes territory held by the ISIL, also known as ISIS, in Syria and Iraq.
Telegram is a free Russian-designed messaging app that lets people exchange messages, photos and videos in groups of up to 5,000.
The deputy prime minister says authorities have found YouTube, WhatsApp and Instagram are used by Islamic State.
"We are trying to support their business but we also need their co-operation in addressing our concerns ie in addressing negative content", he said.