Majid Takht-Ravanchi, deputy foreign minister for European and US affairs and a member of Iran's nuclear negotiations team, made the remarks during a meeting with Czech officials in Prague.
"As long as the P5+1 are sincere and they have a constructive approach, we can reach a good result before November 24," the official IRNA news agency quoted him as saying.
Takht-Ravanchi was referring to the five permanent members of the UN Security Council (Britain, China, France, Russia, the United States) and Germany, with whom Iran has been negotiating since last year.
New talks between Iran and the P5+1 nations will start in New York on September 18, with outgoing European Union foreign policy chief Catherine Ashton chairing the discussions.
The West has long accused Tehran of seeking to develop a nuclear bomb, an allegation that the Islamic republic has consistently denied, insisting its nuclear activities are purely for civilian energy purposes.
The two sides struck an interim deal last November under which Iran agreed to curbs on some parts of its nuclear program in exchange for limited sanctions relief. However the talks later ran into difficulties and a July deadline for a final accord was missed. The discussions were extended until November 24.
The central sticking point in the talks is the level of uranium enrichment Iran would be allowed to conduct under a nuclear deal. In exchange for agreeing to limits, Tehran wants sanctions to be lifted.
The New York talks will be held on the sidelines of the UN General Assembly opening, with the US side being led by Under Secretary Wendy Sherman.
State Department deputy spokesperson Marie Harf said she was unsure when foreign ministers, including US Secretary of State John Kerry and Iranian counterpart Mohammad Javad Zarif, would gather around the table.