Prime Minister Alexis Tsipras, who delivered his shock referendum call in a televised address early Saturday, will address parliament later, with a vote on whether to go ahead with the plebiscite scheduled for midnight.
The bombshell shocked the nation, with people reportedly rushing to withdraw money in fear of capital controls and more financial chaos after nearly six years of crisis and deep recession.
Tsipras' radical leftist Syriza party urged Greeks to vote against the deal, arguing it would worsen austerity in a nation already buckling under economic hardship.
In Greece's second city, Thessaloniki, some banks have run out of money, according to an AFP reporter, while a National bank branch had a queue of 50 people.
Also Read
"I have a shop. I came to the bank to withdraw as much money as I can in order to cover the needs of my shop for next week," 42-year-old Maria Kalpakidou told AFP.
"If we don't have an agreement by July 4, the Greek banking system will crash."
"In the last election I voted for Syriza. But we voted for them to decide, not to transfer responsibility to us, to the Greek people."
Another worried bank customer, Sofia Makridou, told AFP that there is "great uncertainty and insecurity for what may happen", adding it is "rational that there is a bit of a panic".