"We are ready to help the Greek people, but we are by no means willing to help the Greek government," Schultz said, commenting on a decision by Athens to hold a national referendum on Sunday.
According to him, the Greek authorities have showed themselves as incapable of sticking to the agreements reached with international lenders.
Referring to Greek Prime Minister Alexis Tsipras, Schultz described his behavior as "dangerous and irresponsible".
Earlier, Tsipras announced a nationwide referendum on whether his country should accept its creditors' demands for spending cuts and tax increases.
If the Greek government and its international creditors fail to agree on an extension of the bailout program, the country will default on its debt.
After Tsipras announced the July 5 referendum, Greek citizens queued up to withdraw money from their bank deposits.
This prompted the Greek government to declare a week long closure for bank banks, the imposition of capital controls and the banning of international online payments.


