"We want to stop illegal immigration while living up to our humanitarian responsibilities," Merkel said after talks in Vienna with counterparts along the Balkan migrant route.
"It is necessary to get agreements with third countries, especially in Africa but also Pakistan and Afghanistan... so that it becomes clear that those with no right to stay in Europe can go back to their home countries," she told reporters.
In March the EU and Turkey struck an accord under which Ankara promised to halt a mass influx of migrants into Greece in return for billions in aid and other sweeteners.
The influx has far from stopped, however, with many migrants attempting treacherous sea crossings from Libya or Egypt to Italy instead.
More than 300,000 migrants have crossed the Mediterranean this year, the UN said on Tuesday, down from 520,000 from the first nine months of 2015. But deaths this year -- 3,500 so far -- could exceed last year's total.
In addition more than 60,000 migrants remain stranded in Greece. Merkel said that an RU relocation scheme to share out some of these people among EU states has been "too slow".