The ministry "strongly condemned the illegal and unjustified action by the US Treasury Department in sanctioning Mohammad Reza Raouf Sheibani, Iran's designated ambassador to Beirut," the statement said.

The United States on Thursday imposed sanctions on Hezbollah-linked individuals as well as the Iranian diplomat over Lebanon-related activities.

The foreign ministry described the move as "another example of the rogue behaviour and disregard of the US ruling establishment for the fundamental principles of international law and the United Nations Charter".

Lebanon had declared Sheibani persona non grata and ordered him to leave the country in March, but it is not known whether he ever departed from Beirut.

The move came after Hezbollah drew Lebanon into the Middle East war on March 2 when it began striking Israel in response to US-Israeli strikes on Iran.

Iran also condemned the US sanctions on Hezbollah MPs in Lebanon.

"These despicable measures are aimed at undermining Lebanon's national sovereignty and sowing discord within Lebanese society, and are a sign of the continued complicity of the US ruling establishment with the aggressive and occupying Zionist regime (Israel)," the statement said.

The sanctions come amid stalled efforts to formally end the conflict involving Iran, Israel, the United States and Tehran-backed armed groups including Hezbollah.

The war erupted after the United States and Israel launched attacks on Iran on February 28, prompting Tehran to retaliate with missile and drone strikes across the region.

A ceasefire has been in place since April 8 but negotiations to permanently end the war have yet to yield a deal.