The top US negotiator for the Iranian nuclear agreement says Washington wants to start a dialogue with Tehran about the years-long crisis in Syria.

Under Secretary of State for Political Affairs Wendy Sherman told reporters on Friday in Washington that US Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif would probably discuss the topic on Saturday when they meet at the United Nations.

There will be “at least some listening if not some talking” about the Syrian crisis and other regional issues, Sherman added.

“We’ve always been open to having discussions on the margins as appropriate,” she noted.

“Not because we coordinate but we certainly know that there are parallel interests,” the US official stated.

“There are great political sensitivities in Iran to having these discussions and probably some limits that are real, but it is important to engage to the extent that we can,” she opined.

Syria has been gripped by deadly violence since March 2011. According to reports, the United States and its regional allies - especially Qatar, Saudi Arabia and Turkey - have been supporting the militants operating inside Syria since the beginning of the crisis.

Sherman, who helped guide the Iran nuclear agreement through months of intense negotiations, said Kerry and Zairf are also excepted to discuss the implementation of the nuclear deal reached between Iran and the P5+1 group -- the United States, Britain, France, China, Russia and Germany –  on July 14 in the Austrian capital of Vienna.

The US Congress has reviewed the Iran nuclear agreement and voted on it.

On September 17, US Senate Democrats blocked a resolution against the Iran agreement for a third time, sealing a major foreign policy victory for President Barack Obama.

The Republicans failed to gather the 60 votes needed for the resolution of disapproval in the 100-member chamber.

Thursday's vote came after Democrats previously blocked the resolution of disapproval from moving forward twice in the Senate.