"That will be one of the hard issues", German Finance Minister Wolfgang Schaeuble said.
German Chancellor Angela Merkel stands in the way of the debt relief, as she refuses to unlock more loans to Greece.
Ministers from the 19-member eurozone will discuss the subject at talks in Brussels later on Monday after Greek MPs fulfilled the latest demands for reforms in a vote last Thursday, giving the go-ahead for a further austerity package that includes pension reductions and tax increases.
May 22 A decision on debt relief for Greece will only be taken at the end of the bailout in mid-2018, but euro zone finance ministers may agree already on Monday to release new loans to Athens, the chairman of the ministers Jeroen Dijsselbloem said.
Gabriel, a Social Democrat, said Greece has upheld its side of the bargain by passing the latest measures to meet bailout terms, meaning it's time for creditors to end "political blockades" and flesh out plans for possible debt relief envisaged in 2018.
Macron told Tsipras he was in favour of "finding a deal soon to alleviate the weight of Greece's debt over time", a statement from the presidenct said.
The meeting will be the first for French Finance Minister Bruno Le Maire, named to his post last week by Macron, a pro-EU centrist.
GettyGermany's Foreign Minister Sigmar Gabriel has called for the bailout to go ahead
Mr. Schaeuble later described reforms agreed by Greece as "remarkable" but said the Greek economy was not yet competitive and that Athens must press ahead with implementing its existing reforms-for-aid programme.
The Eurogroup also said at the time it would consider replacing more costly International Monetary Fund loans to Greece with cheaper euro zone credit and transfer the profits made from a portfolio of Greek bonds bought by euro zone national central banks back to Athens.
Greece is now in the midst of its third bailout programme - the current three-year deal expires in the summer of 2018 and could be worth up to €86bn in total.
Though Greece emerged from its economic depression in 2014 and its annual budget position has improved dramatically, the economy is back in recession, having shrunk for two straight quarters.
Speaking at a regular government news conference, Foreign Ministry spokesman Martin Schaefer said institutions such as the International Monetary Fund and the European Commission were not far apart in their assessment on Greece.
The country's debt burden stands at around 175%, a level that the Greek government thinks is unsustainable in the long-term - hence its insistence on some debt relief, at least in the form of lower interest payments and longer repayment terms.
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