Chancellor Angela Merkel and President Francois Hollande met to discuss how to deal with Greece before Prime Minister Antonis Samaras visits both of them over the next two days.
Earlier in the day, Germany's finance minister set the stage for tough negotiations by claiming that giving Greece more time to make reforms would achieve little.
As creditors' impatience grows with Greece, Merkel's government is reluctant to offer significant concessions, but Hollande has generally taken a softer line in the debt crisis afflicting Greece and several other countries in the 17-nation eurozone.
In a charm offensive in German and French media this week, Samaras has been arguing that his nation should have more time to complete reforms that are a condition of it continuing to receive bailout loans. Without the help, Greece would be forced into a chaotic default on its debts and could be forced out of the eurozone.
In brief statements to reporters at the chancellery in Berlin, Merkel and Hollande didn't directly mention Samaras' calls — but made clear that it is first and foremost up to Greece to satisfy its creditors.
Athens has faltered in the speed and effectiveness of implementing the reforms, irritating its creditors, notably Germany, which is the single largest contributor to its €240 billion ($300 billion) bailout packages. Weeks of political wrangling in Greece that ultimately brought a coalition government under Samaras to power didn't help.
Greece's continued access to the bailout packages hinges on a favourable report next month from the so-called "troika" of the country's debt inspectors — the European Union, European Central Bank and the International Monetary Fund. If Greece is found to have failed on key economic reforms that are conditions of the bailout loan, vital funds could be halted.
"For me, it's important that we all stand by our commitments, and in particular await the (publication of) the troika report, to then see what the result is," Merkel said. "But I will encourage Greece to follow the path of reform, which demands a lot of the Greek people."
Hollande stressed: "I want Greece to remain in the eurozone. That's my wish. That's our wish." But he added that "of course Greece must make the necessary efforts for this to happen."
Samaras visits Berlin on Friday and Paris on Saturday.
Germany's finance minister noted that it's only a few months since creditors drew up a second bailout package and agreed on a massive debt writedown for Greece.
"You cannot just say after half a year, all of that is not enough, because then you will never win the confidence of financial markets," Wolfgang Schaeuble said on Germany's SWR radio. "So more time is not a solution for the problems. The question is how we win back confidence."
Schaeuble made clear his skepticism over Samaras' argument that giving Greece more time doesn't have to mean giving it more money.
The existing program for Greece "must be implemented, and in case of doubt more time means more money," he said. "And more money would require a new program."
Leading lawmakers in Merkel's centre-right coalition have made clear that they oppose drawing up a third rescue program for Greece.
"With the program last year for Greece we went to the limits of what is economically justifiable," Schaeuble said. "It is not about more or less generosity — it is simply about finding a common way to lead this eurozone as a whole out of this growing lack of confidence on the financial markets."
Some German politicians — though not Merkel or Schaeuble — have talked openly in recent weeks about the possibility of Greece leaving the euro, and the vice-chancellor, Economy Minister Philipp Roesler, has said that the idea of a Greek exit has "lost its horror." Germany is the largest single contributor to Greece's bailout packages.
Merkel so far has said little specific about Europe's options on Greece. But in a video message for the launch Thursday of a campaign by 11 German think tanks entitled "I want Europe," Merkel sought to address growing unease among many Germans about the political future of the continent.
Merkel stressed that "Europe is our future ... protecting and preserving this idea was and is worth every trouble and effort."
The crisis built up over years, "so the road toward overcoming it is necessarily long, too," she added. "But I am firmly convinced that, at the end of this road, there will be an enduringly strengthened eurozone and an enduringly strengthened European Union."
Frank Jordans and David Rising contributed to this report.