The closure was enforced on June 29, following the collapse of aid negotiations.
Greek banks have enough liquidity in cash machines to serve the public until Monday, Louka Katseli, head of the Greek bank association said on Thursday.
"We know that everything is secured until Monday," Katseli told Greece's Skai TV.
Greek authorities have extended a shutdown of the country's banks until July 13, restricting cash withdrawals to 60 euros per day.
The closure was enforced on June 29, following the collapse of aid negotiations between Greece and international creditors.