During the two-day meeting, the two sides’ experts will try to finalize measures prior to the implementation of the deal, dubbed as the Joint Comprehensive Plan of Action (JCPOA).
The Iranian delegation is chaired by Foreign Ministry's Director General for International and Political Affairs Hamid Baeedinejad.
Negotiations started as US officials are talking about new sanctions on Iran. Talk of new US sanctions against Iran emerged after the Islamic Republic successfully test-fired a precision-guided long-range missile on October 11, 2015.
Several US politicians have said the test violated a United Nations resolution against Iran, and called on the US administration to introduce new sanctions against Tehran.
Fearing Iran's reaction, the White House delayed implementing the sanctions for an unspecified time.
The sanctions would be the first ever since Iran and the Group 5+1 (also known as P5+1, E3+3) reached the nuclear deal in July 15, 2015.
The agreement would see the removal of nuclear-related sanctions against Iran in return for enhanced transparency by Iran in its peaceful nuclear program.