Germany urged the world community meeting at the UN General Assembly in New York on Tuesday to stand together to find a way to end the war in Syria and stop Iran from getting a nuclear bomb.
Foreign Minister Guido Westerwelle said Iran should face tougher economic sanctions targeting its financial, trade, transport and energy sectors to force it to engage in serious negotiations on its alleged weapons program.
"Iran has not taken advantage of the talks in the past months to negotiate substantially," Westerwelle said on the sidelines of the UN summit, adding: "A nuclear armed Iran is unacceptable."
Westerwelle was speaking just ahead of a speech by President Barack Obama at which the US leader was expected to say that the United States would "do what we must" to prevent Iran from obtaining nuclear weapons.
But the German diplomat stopped short of endorsing military options, and said there was still time for diplomacy to work.
On Syria, Westerwelle called for a "clear and joint signal" during the UN General Assembly week to pressure Bashar al-Assad's regime and his opponents bring an end to the 18-month conflict.
But he tried to keep expectations low, deploring that a standoff over Syria in the Security Council between Western nations on one side and Russia and China on the other had led to the "paralysis of the international community".