International Monetary Fund Managing Director Christine Lagarde said that a new program to prop up Greece's finances would require creditors to restructure debt.
Greek banks will remain closed until Monday, the finance ministry said as the government raced to come up with a new proposal to present to creditors in a last-minute drive to avert a eurozone exit.
Russian President Vladimir Putin is to meet world leaders including China's Xi Jingping and India's Narendra Modi ahead of the start of a summit of the BRICS emerging economies.
Greece's economic turbulence is dominating political debate in Spain ahead of a year-end general election, with the ruling conservatives pointing to Syriza's difficulties to discredit its Spanish ally Podemos.
German Chancellor Angela Merkel said that there was still no basis for talks on a new Greek bailout, as she arrived in Brussels for an emergency summit of eurozone leaders.
International Monetary Fund chief Christine Lagarde said that the global crisis lender would assist Greece if asked, a day after Greek voters rejected a prior bailout plan.
Greek Foreign Minister Nikos Kotzias ruled out his country's exit from the EU and called for calm after Greek voters rejected bailout terms of international creditors.
The euro rose after Greece's Finance Minister Yanis Varoufakis announced his shock resignation, just hours after the cash-strapped nation rejected creditors' austerity demands in a landmark weekend referendum.
Greece has moved a step closer towards a eurozone exit as early results from a crucial bailout referendum suggested Greeks had overwhelmingly rejected creditors' demands for more austerity.
Greece will have to introduce another currency if it votes 'No' in Sunday's referendum on its potential bailout terms, European Parliament president Martin Schulz said.
EU president Donald Tusk urged the bloc to avoid sending any "dramatic messages" even if the Greeks were to vote against bailout conditions in their weekend referendum.
Malaysia's premier Najib Razak on Friday dismissed as "political sabotage" a report that a probe into a state-owned investment fund had found hundreds of millions of dollars were transferred to his personal bank accounts.