Both of them. The new Greek government was not ready to default and exit the euro, because it knows that while it has full backing to confront the EU over its bailout terms and the failed austerity programme, it does not have a majority to exit the eurozone. Yet. But if the demands are too steep that will change. So to buy time it gave ground.
Germany looked at the bill if Greece dropped out of the euro and also looked at the blow to its own leadership of Europe if that happened. It would be blamed for the disaster and moreover would face further huge investments to keep Italy, Spain and Portugal from following Greece out. Merkel sees this, but she has trouble with her finance minister who sees only financial rectitude and reform. So she has manged to get a deal which will push Greece to the limit of its democratic mandate. It is the fine judgement of what that limit actually is which will determine whether the battered euro edifice remains standing, or whether bit by bit it tumbles down.