European Central Bank (ECB) promises to support the euro will not be an excuse for Greece to ease up on efforts to tackle its economic crisis, David Cameron and Francois Hollande said.
In a phone call, the Prime Minister and French president welcomed the ECB's stance but said this "did not negate" the need for Greece to stabilise its economy.
Mr Cameron also discussed the situation with US president Barack Obama, with the pair welcoming the ECB's stance.
Downing Street said Mr Cameron and Mr Hollande "welcomed the recent actions of the ECB and agreed that this did not negate the need for Greece to stabilise their own economy and prevent any further detrimental effects to the wider eurozone".
Along with Mr Obama, the Prime Minister "agreed that it was good news that the ECB was taking action and standing firmly behind the euro".
The phone calls came as Greece pleaded for more time to implement austerity measures.
Greek Prime Minister Antonis Samaras asked for "a little air to breathe" as the nation faced up to spending cuts and financial reforms.
Before a series of high-level meetings with European leaders, Mr Samaras said Greece needed more time to restart its economy but this did not necessarily mean it needed more funds.
He told the Bild newspaper in Germany: "Let me be very clear: we are not asking for extra money.
"We stand by our commitments and the implementation of all requirements. But we must encourage growth, because that reduces the financing gaps."
He added: "All we want is a little 'air to breathe' to get the economy going and increase state income."
