He made the statement in a joint press conference following a meeting in Tehran on Tuesday evening with Iranian Foreign Minister Mohammad Javad Zarif during which he said his second visit to Tehran in three months focused on good issues as well as those which are a source of concern.
On regional crises, the German foreign minister called for a change in the conditions so that bloodshed can be stopped and a political solution is achieved.
"'I am confident the JCPOA made the world and region safer, and for the years to come narrowed prospects of nuclearization of the region,' he said expressing his satisfaction over the deal reached between Iran and world powers in Vienna last summer."
'It is why we say that JCPOA is important,' he added.
He said it is not a secret that there are differences over the settlement of the Syrian crisis. 'We shall act upon the understanding reached under UN supervision so that it will result in negotiations between the Syrian government and its opposition.'
The German foreign minister said that Iran and Saudi Arabia are the two countries that can contribute to the settlement of crisis in Syria and that he will visit Riyadh on Wednesday.
To a question on Germany's likely mediation between Iran and Saudi Arabia, Steinmeier said, 'I think it is not necessary that I want to mediate between two neighboring countries of Iran and Saudi Arabia or that they need a mediator.'
He also said that in his scheduled meeting with President Hassan Rouhani on Wednesday, the issue of his next state visit to Europe will be discussed, IRNA reports.
Future of Syria will be determined by the people of Syria
Syria also dominates this joint news conference with both reiterating their country's positions as a U.N.-led effort to bring the warring parties to the negotiating table falters in Geneva.
"Zarif added: "Unfortunately, some of our neighbours still think, and they still have the illusion that the Syrian crisis can be resolved militarily, and that is why they have blocked the peace process and are continuing their sabotage.""
Iranian Foreign Minister Mohammad Javad Zarif said: "Tensions in this region are not beneficial to anybody. Supporting extremism and sectarianism in this region is not beneficial for anybody, and Saudi statesmen would lose more than anybody else. Once more, we advise our neighbours that the Islamic Republic of Iran is a great power in this region that has sought, and is seeking rational relations and constructive relations with all of its neighbors. Others should stop the existing agitation that has been due to positive results of the JCPOA, and we do not know the reason for it, and they should come to rationality”, Reuters reports.
Iranian Foreign Minister said: "The Islamic Republic of Iran believes that the future of Syria will be determined by the people of Syria, and nobody else has the right to make decisions about Syria's future. The future of Syria will be determined at a negotiation table among the Syrians, and neither before the talks, nor as a preconditions of the talks. Those who had set forth preconditions for the talks on Syria have been responsible for continuation of bloodshed and war during the past three years."