Renegotiations have become "possible" for the Greece government and the creditors after the Sunday's Greek referendum showed a strong lead of NO on the creditors bailout offer.
"The NO side has won the referendum with an overwhelming majority, we have to respect the vote of Greek people," European Parliament President Martin Schulz said in a statement.
He argued that a "NO" vote would not entail a better deal as Greek Prime Minister Alexis Tsipras has promised to his people. "Greek people said NO, but 18 members of euro zone agreed about the proposals," he said.
Schulz said that an immediate renegotiation is "necessary" and "possible" but depends on Greek proposals.
He urged the Greek government to make "meaningful" and "possible" proposals in coming hours for renegotiation, saying that "it is now up to Greek government to make proposals to convince the other 18 member states of euro zone and the institutions in Brussels."
German Chancellor Angela Merkel and French President Francois Hollande are due to meet on Monday in Paris to assess the outcome of referendum.
Meanwhile, leaders of Greece's lenders in Euro zone, namely Jean-Claude Juncker, the President of the European commission, Donald Tusk, the President of the Euro Summit, Jeroen Dijsselbloem, the President of the Euro Group and Mario Draghi, the President of the European Central Bank, will hold a conference call on Greece as the Greek referendum showed a lead of NO on their offer, said the European Commission in a statement.
The Eurogroup head said late Sunday night the Eurogroup will discuss state of play on Tuesday.
"I take note of the outcome of the Greek referendum. This result is very regrettable for the future of Greece," Dijsselbloem said in a statement.
"We will now wait for the initiatives of the Greek authorities. The Eurogroup will discuss the state of play on Tuesday 7 July," he added.
But some officials like Axel Schaefer, Merkel's ruling partner in her coalition government argued that the situation was too serious to be left to finance ministers. So the President of the European Council called for another Euro summit on Greek debt issue.
"I have called a Euro summit Tuesday evening at 18h to discuss situation after referendum in Greece," Tusk tweeted.
With about 61.3 percent of the votes counted, the "NO" side in Greek referendum had won 61.3 percent, according to the latest official estimate released by Greek Interior Ministry.
According to local media, Greek negotiating team was ready to travel to Brussels and the government assured that dialogue with lenders would resume from Sunday night.
Earlier Greek ministers said that the government wanted a debt deal within 48 hours, as the country's banking system was under unprecedented pressure.
Since last Monday Greek banks have been closed and capital controls imposed to avert the sector's collapse after the European emergency liquidity aid to the local banking system was cut off.
Greek officials have admitted that ATMS will run out of cash on Monday with no more financial support from creditors.