Steinmeier arrived in Ankara following a breakthrough agreement on Thursday in Vienna on a package of incentives designed to persuade Iran to halt its nuclear program.
Steinmeier and his Turkish counterpart, Abdullah Gul, were expected to jointly urge Iran - Turkey's eastern neighbor - to agree to the package of incentives and avoid a standoff.
Steinmeier met with Prime Minister Recep Tayyip Erdogan and was scheduled to meet with Gul and President Ahmet Necdet Sezer later on Friday.
In Vienna, six world powers, including Germany, agreed on a package of incentives in a bid to persuade Iran to halt its nuclear program, and said U.N. Security Council action against Tehran would be suspended if it agrees to stop enriching uranium.
Turkey has urged Iran to cooperate with the international community, saying it would act along with Security Council decisions on the issue.
During Friday's talks with Steinmeier, Turkish leaders were also expected to ask for Germany's support for Turkey's EU bid, the AP reports.
German Chancellor Angela Merkel opposed EU membership for Turkey before she came to power last year, saying the country should be offered a "privileged partnership" instead. However, her Social Democrat coalition partners support Ankara's bid and Merkel's government has since said it supports the country's ongoing membership talks.
There are several versions of the recent assassination of the most prominent Iranian nuclear scientist and high-ranking officer of the Islamic Revolutionary Guard Corps, Mohsen Fakhrizadeh