|Is the party over for Greece?|
The Greek government earlier rejected the proposals, aimed at avoiding the country defaulting on its debt.
Greece has to make a €1.5bn ($1.7bn; £1.06bn) IMF debt repayment on 30 June.
In the speech, Mr Tsipras said: "These proposals, which clearly violate the European rules and the basic rights to work, equality and dignity show that the purpose of some of the partners and institutions was not a viable agreement for all parties, but possibly the humiliation of an entire people."
"The people must decide free of any blackmail," he added.
Read more: Greece debt crisis: Tsipras announces bailout referendum - BBC News