German Economy Minister Sigmar Gabriel urged the Iranian government during his two-day visit to the Islamic Republic to do what it can to push for a ceasefire in Syria.
Syrian President Bashar al-Assad's forces, supported by Iranian-backed militia and Russian air power, have stepped up an offensive against rebel-held areas of Aleppo, Syria's biggest city, bombing hospitals and damaging water supplies.
"We have of course asked the government to do everything it can to push for a ceasefire," Gabriel told reporters late on Monday after meeting Iranian politicians.
He said he had made clear that no one in Germany could understand that hospitals were being bombed and civilians were suffering.
Everyone who supports the Syrian government "and that includes Iran" shares responsibility for ending the fighting, he said. "I think Iran knows its responsibility there," he said.
The United States broke off talks with Russia on Monday on implementing a ceasefire agreement in Syria, suggesting there is little hope of a diplomatic resolution to the 5-1/2 year-old conflict that has killed hundreds of thousands of people and displaced 11 million.
"The ending of talks ultimately is a testament to our joint helplessness," Gabriel said.
Gabriel is leading a delegation of business executives to Iran encourage business deals after a historic nuclear accord paved the way for ending sanctions that had been in place for years. On Monday, Siemens signed a contract to upgrade Iran's rail network.