Steinmeier's visit follows on from a three-day trip last month by Economy Minister Sigmar Gabriel, who became the first senior figure from a large Western government to visit Tehran since it struck a landmark nuclear agreement with world powers, Reuters reported.
"I will be in Iran in October," Steinmeier said at the opening of a diplomatic conference in Berlin on Monday. A German Foreign Ministry spokesman said talks about the trip were just starting and he could not give any concrete details.
Germany has commercial and cultural links in Iran that go back to the 19th century. German firms were involved in almost every major industrial project in Iran until its 1979 Islamic Revolution, including the Trans-Iranian Railway.
Western politicians have hurried to visit Tehran to reinvigorate business and diplomatic ties since the nuclear agreement. On Sunday, Britain reopened its embassy in Tehran.