9.08pm BST

The Washington Post has a transcript of Obama's statement on the call with Rouhani, which does not appear to be on the whitehouse.gov site yet. At the end is a paragraph on Syria:

Before I just discuss the situation in Congress, let me say a few things about two important opportunities in our foreign policy.

Just now I spoke on the phone with President Rouhani of the Islamic Republic of Iran. The two of us discussed our ongoing efforts to reach an agreement over Iran’s nuclear program. I reiterated to President Rouhani what I said in New York. While there will surely be important obstacles to moving forward and success is by no means guaranteed, I believe we can reach a comprehensive solution.

I’ve directed Secretary Kerry to continue pursuing this diplomatic effort with the Iranian government. We had constructive discussions yesterday in New York with our partners, the European Union, the United Kingdom, France, Germany, Russia and China, together with the Iranian foreign minister. Going forward, President Rouhani and I have directed our teams to continue working expeditiously, in cooperation with the P-5 plus one, to pursue an agreement. And throughout this process, we’ll stay in close touch with our friends and allies in the region, including Israel.

Now, we’re mindful of all the challenges ahead. The very fact that this was the first communication between an American and Iranian president since 1979 underscores the deep mistrust between our countries, but it also indicates the prospect of moving beyond that difficult history.

I do believe that there is a basis for resolution. Iran’s supreme leader has issued a fatwa against the development of nuclear weapons. President Rouhani has indicated that Iran will never develop nuclear weapons. I’ve made clear that we respect the right of the Iranian people to access peaceful nuclear energy in the context of Iran meeting its obligations.

So the test will be meaningful, transparent and verifiable actions, which can also bring relief from the comprehensive international sanctions that are currently in place.

Resolving this issue, obviously, could also serve as a major step forward in a new relationship between the United States and the Islamic Republic of Iran, one based on mutual interest and mutual respect. It would also help facilitate a better relationship between Iran and the international community as well as others in the region, one that would help the Iranian people fulfill their extraordinary potential but also help us address other concerns that could bring greater peace and stability in the Middle East.

A path to a meaningful agreement will be difficult. And at this point both sides have significant concerns that will have to be overcome. But I believe we’ve got a responsibility to pursue diplomacy and that we have a unique opportunity to make progress with the new leadership in Tehran.

I also communicated to President Rouhani my deep respect for the Iranian people.

Now, as I said before, this comes on the same day that we can accomplish a major diplomatic breakthrough on Syria as the United Nations Security Council will vote on a resolution that would require the Assad regime to put its chemical weapons under international control so they can ultimately be destroyed. This binding resolution will ensure that the Assad regime must keep its commitments or face consequences. We’ll have to be vigilant about following through, but this could be a significant victory for the international community and demonstrate how strong diplomacy can allow us to secure our country and pursue a better world.