Earlier in the day, UK Foreign Secretary Philip Hammond said upon his arrival to Vienna there was no breakthrough yet in the Iran nuclear talks.
"The negotiations are so difficult. They are not only very extended in time, but also very difficult. All i can assure you is that my impression is that all of us here in Vienna are seriously prepared to come to a result," Steinmeier said
He added that there are obstacles the sides were trying to remove and the last steps toward an agreement will be the most difficult.
Despite the difficulties, the minister expressed certitude that the discrepancies between the sides would be overcome.
"I am optimistic that we will have a meeting with ministers," Steinmeier pointed out.
In April, as Iran and the P5+1 group, comprising Russia, China, France, the United Kingdom, the United States and Germany, signed a political framework deal, Tehran agreed to cut back uranium enrichment and decrease its number of centrifuges in exchange for sanctions relief.
At the center of this last round of talks in Vienna between the six world powers and Iran are the timing of sanctions relief and the mechanisms to ensure Tehran's compliance with the agreement.
The date for the ministerial meeting of all the negotiating process's participants to sign the final agreement has not been set yet.
