Speaking in Zambia, where he is partway through a four-day tour of several African countries, Steinmeier confirmed the release of the two hostages.
He neither confirmed nor denied whether other German citizens were among those held at the hotel.
"We have no complete picture yet. Reconnaissance is proceeding at full speed," Steinmeier told journalists.
All diplomats from the German embassy, as well as German UN workers and those working for development organizations were accounted for, he said.
Armed men stormed the Radisson Blu Hotel near central Bamako on Friday morning, taking 170 people hostage.
A number of the hostages have since been freed, including 12 staff from Air France.
France has sent a team from its elite counter-terrorist GIGN police to help forces on the ground, including French and American troops, deal with the hostage-taking.
Reports late on Friday afternoon suggested that 18 people had been killed in the hotel. Malian authorities said there were no hostages left in the gunmen's power.
A small number of German soldiers are in Mali to assist in an EU mission to train local forces.
France intervened suddenly in the west African nation in early 2013, when military officers toppled the government as Touareg rebels from the north of the country threatened to overrun the capital.
Speaking with DPA on Friday, Defence Minister Ursula von der Leyen said that "if other nations show more engagement [in Mali], the French will have more capacity to fight against Islamist terror in other places."
German soldiers are slated to take a bigger role in the training mission from early next year, with up to 350 soldiers potentially headed to a training camp north of Bamako.
Just nine German soldiers are involved in the UN peace mission Minusma, although up to 700 may be sent next year, von der Leyen said.