Eurozone finance ministers say they expect to hear new proposals from Greece after the country voted to reject the terms of an international bailout.
Eurogroup President Jeroen Dijsselbloem described the referendum result as “very regrettable for the future of Greece”.
Ministers are to hold emergency talks on Tuesday.
Earlier, Greece’s outspoken finance minister, Yanis Varoufakis, resigned.
He said that eurozone finance ministers, with whom he had repeatedly clashed, had wanted him removed.
Meanwhile, the European Central Bank (ECB) is to discuss whether to raise its emergency cash support for Greek banks, which are running out of funds and on the verge of collapse.
Global financial markets have fallen over fears that Greece is heading for an exit from the euro.
Media caption Greek economy minister Giorgos Stathakis: ‘Banks have cash for a number of days’
In his statement, Mr Dijsselbloem said: “For recovery of the Greek economy, difficult measures and reforms are inevitable. We will now wait for the initiatives of the Greek authorities.”
German Chancellor Angela Merkel’s spokesman Steffen Seibert said there was currently “no basis” for talks on a new bailout package and the ball was in Greece’s court.
“It is up to Greece to make something of this. We are waiting to see which proposals the Greek government makes to its European partners,” he said.
Mrs Merkel is to meet French President Francois Hollande in Paris on Monday.