Iranian supreme leader Ayatollah Ali Khamenei warned Western leaders on Monday of a "firm fist" and a "negative impact" on relations in response to their "meddling" in Iran's domestic affairs.
The comments by Khamenei reflect continued efforts by the regime to blame Western powers such as the US and Britain for widescale unrest following the country's disputed presidential election.
They also come one day after the American vice president said the US is still open to negotiating with Iran over its nuclear program.
"Some leaders of Western countries at the level of president, prime minister and foreign minister openly intervened in Iran's internal affairs that had nothing to do with them.
"Then, they said they don't intervene in Iran's internal affairs," the television quoted Khamenei as telling thousands of Iranians during a ceremony to commemorate a revered Shiite saint.
Khamenei added that western governments must be careful of their "hostile remarks and behaviors" because Iran will react.
"We will calculate the interventionst remarks and behaviors of these governments. Definitely, it will have a negative impact on future relations with the Islamic Republic of Iran.
"The leaders of arrogant countries, the nosy meddlers in the affairs of the Islamic republic, must know that no matter if the Iranian people have their own differences, when you enemies get involved, the people... will become a firm fist against you," he said in a televised speech.
"The Iranian nation warns the leaders of those countries trying to take advantage of the situation, beware! The Iranian nation will react."
Iranian leaders have accused the West, particularly Britain and the United States of seeking to destabilize the country in the aftermath of its disputed presidential election.
Iran quashed street protests following its disputed June 12 election and the leadership has been trying to erase any lingering doubts about the legitimacy of President Mahmoud Ahmadinejad by portraying the unrest as sparked by foreign meddling, not by public anger.
AFP and AP contributed to this report