Dozens of people gathered by a large Christmas tree at Brandenburg Gate in Berlin to hold a vigil for the victims of the attack at Breitscheidplatz.
Tributes of candles, messages and flowers lay by the tree, which was lit up in white Christmas lights. Those attending the service brought candles and lanterns, which they held as they stood together near the famous German landmark.
Many hugged and wept as the vigil took place.
John Lennon's song Imagine was played after a short speech by Anne Wizorek, an author in Berlin.
"We need radical solidarity," she told the crowd. "We have to stand together and not be torn apart.
"We cannot let the hate and the fear have a platform.
"You will not receive our hatred - not in Berlin and not anywhere else in Germany."
A minute's silence was held at the service, which took place at the same time as others in Munich, Hamburg and Frankfurt.