"The crisis considerably strengthened the anti-immigration opposition, divided the ruling coalition and weakened Berlin's role in the European Union," the report stated.
On Sunday, three German federal states — Baden-Wuerttemberg, Rhineland-Palatinate and Saxony-Anhalt — held elections for regional parliaments.
The ruling party of German Chancellor Angela Merkel, the Christian Democratic Union, lost votes in all three election contests.
Merkel has attributed her party’s weak performance to the issue of migration, which she said there is not yet a final and satisfactory solution.
"The weak support shown for Germany's traditional parties on March 13 will only further hurt Germany's leadership in the European Union as well," the report concluded.
The European Union is struggling to manage a massive influx of migrants as millions of people are leaving the Middle East and North Africa but also other regions as well.
The Merkel government has faced severe criticism over its open-door migration policy, especially after a high-profile series of attacks on women by the migrants in Cologne on New Year's Eve.