Greece has about 7.5 billion euros of debt falling due by July, which it is unable to pay without more loans from lenders.
So far it has received some 31.7 billion from the latest bailout accord, its third since 2010.
Disagreements over labor and energy market reforms lenders want Greece to adopt have been complicated by broader misgivings from the IMF, which will not participate in the most recent bailout because of concerns Athens will never be able to extricate itself from debt.
European policymakers have said that the bailout programme cannot continue without IMF input, although a Manfred Weber, a German who heads the conservative bloc in the European Parliament, said on Thursday IMF participation is no longer crucial.
The fundamentals of the Greek economy have been strengthened, Dombrovskis said, but that strong growth potential was contingent on reforms being implemented.
"So policy makers are faced with this choice – work hard to reach an agreement that will build on progress made or slip back into uncertainty. I think the choice is obvious," he said.
Recent Greek economic data has shown how tenuous the recovery is, with inflation rising and economic growth contracting again.
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