The assailants tore pages of a copy of Quran at Barbaros Mosque of the Turkish Islamic Union for Religious Affairs (DITIB).
DITIB representative Sebahattin Cigdem said on Wednesday an investigation into last night's attack was launched after they saw a copy of Quran ripped up inside the mosque and called the police Wednesday morning.
In the last 10 days in Germany, six DITIB mosques as well as an Arab mosque were attacked.
Germany has witnessed growing Islamophobia and hatred of migrants in recent years triggered by the far-right parties, which have exploited fears over the refugee crisis and terrorism.
Police recorded 813 hate crimes against Muslims last year. At least 54 Muslims were injured in those attacks carried out mostly by far-right extremists.
Germany, a country of over 81 million people, has the second-largest Muslim population in Western Europe after France.
Source: Anadolu Agency