Iran on Tuesday deplored the military chief of the US Central Command, General David Petraeus, for saying that the Islamic state had become a "thugocracy."
Petraeus's remarks published on Sunday referred to the suppression of popular protests against alleged fraud in the June presidential election, DPA reported.
The disputed results led to the re-election of President Mahmoud Ahmadinejad, which the opposition has refused to acknowledge.
"Those who use such language and adopt such attitude are the (real) thugs," Foreign Ministry spokesman Ramin Mehmanparast told reporters in Tehran.
He associated Petraeus's remarks with what he called the US failure to launch a so-called "soft war" to topple the Islamic government.
Parliament Speaker Ali Larijani on Tuesday also denounced Petraeus and called the US government "murderous."
The speaker said the Americans were hated in the region for having killed thousands of Iraqis, Afghans and Palestinians.
The war of words between the US and Iran has gained momentum in recent weeks.
US Secretary of State Hillary Rodham Clinton said in a speech last month in Saudi Arabia that the "US sees Iran moving toward a military dictatorship."
Iran rejected the charges and accused the US of supporting terrorism in the region.