Iran and members of the P5-plus-1 -- the United States, Britain, Russia, France, China and Germany -- are scheduled to sit down at the negotiating table Tuesday in Vienna to discuss progress made on an interim nuclear deal.
Ismail Kowsair, chairman of the Iranian Defense Committee, said Thursday negotiators need to stick to a nuclear agenda.
"Negotiating on the country [Iran's] defense capabilities in the upcoming talks between Iran and the [multilateral] group is our red line," he was quoted by Iran's state-funded broadcaster Press TV as saying.
U.S. President Barack Obama and Secretary of State John Kerry said in separate occasions a military option was still on the table if Iran reneges on a November agreement to curb its nuclear research activity in exchange for sanctions relief.
Iran said two ballistic missile tests this week were meant as a response to what it said was the bellicose rhetoric coming from U.S. officials.
White House spokesman Jay Carney Iran's missiles were among the "number of issues" of concern for the U.S. government.