Tehran, Iran (CNN) -- The Iranian supreme leader Thursday accused the United States of "holding a gun" to Tehran's head to pressure it to hold direct talks.
Ayatollah Ali Khamenei told Iranian media that the United States is seeking talks while making threats.
"The new administration, like its predecessors, has repeated the issue of talks between Iran and the U.S. And they say the ball is in Iran's court. The ball is in your court," he told the semiofficial Mehr News Agency.
Last week, U.S. Vice President Joe Biden said that Washington is open to direct talks despite both nations' longstanding dispute over the Iranian nuclear program.
Iran has been the target of various international sanctions, but it has long maintained that its nuclear program is for research and medical needs.
"There has to be an agenda that they are prepared to speak to," Biden said. "We are not just prepared to do it for the exercise."
But Khamenei, Iran's highest authority, said his nation will not be pressured into talks.
"I speak honestly and clearly when I say to you (Americans) that you hold a gun to Iran's head and you expect to engage in dialogue," he told Mehr. "The Iranian nation will not be frightened by these things."
Though the supreme leader's statements appeared to condemn offers of talks that come with pressure, Iran has not indicated that it is not open to dialogue altogether.
Indirect talks with Iran, through the so-called P5+1 group, have been unsuccessful and have stalled for months. The group comprises the five members of the United Nations Security Council and Germany.
Lack of progress in those talks has forced the Obama administration to rethink its diplomatic approach.
Khamenei's message comes a day after the United States took steps to tighten economic sanctions on Iran.
The actions will cut even further the money that Iran can bring in from countries it still sells crude oil to.
Some of these countries have been participating in the sanctions under the "significant reductions" clause of U.S. sanctions laws, which means they made significant reductions in the amount of oil they were buying from Iran.
Countries including China, Japan, South Korea and India have reduced purchases enough to avoid U.S. bank sanctions.