Merkel said that despite efforts to integrate refugees and help them, it was important to stress that they had only been given permission to stay for a limited period of time, Reuters reported.
"We need ... to say to people that this is a temporary residential status and we expect that once there is peace in Syria again, once ISIS (Daesh) has been defeated in Iraq, that you go back to your home country with the knowledge that you have gained," she said at a meeting of CDU members in the state of Mecklenburg-Western Pomerania.
She said 70 percent of refugees that fled to Germany from the war in the former Yugoslavia in the 1990s had returned to their home countries.
Her remarks come after Horst Seehofer, leader of the CSU, threatened to take her government to court if his demand to stem the flow of asylum seekers was not met.
Support for the right-wing Alternative for Germany (AfD) has edged up into double digits. Its leader said in an interview published Saturday that border guards should shoot at refugees to prevent them from illegally entering the country if need be.
Merkel has tried to convince other European countries to take in quotas of refugees, pushed for reception centers to be built on Europe's external borders, and led an EU campaign to try to convince Turkey to keep refugees from entering the bloc.
But progress has been slow.
Germany wants to limit migration from North Africa by declaring Morocco, Algeria and Tunisia "safe countries", which would end their citizens' chance of being granted asylum.
Merkel said she had spoken to Morocco's king and that Morocco had said it was prepared to take back people from that country.