Russian Deputy Foreign Minister Sergei Ryabkov has repudiated new US sanctions on Iran’s businesses, saying Washington appears to be taking every opportunity to exert pressure on countries it dislikes.

The US Treasury Department on Tuesday slapped sanctions on Bank Mellat and Mehr Eqtesad Bank and other companies linked to investment, commodities and engineering.

"Regardless of what reasons, under what pretexts and against which countries the United States imposes its unilateral sanctions, we firmly oppose it,” Ryabkov told Russian state news agency Sputnik.

“The unacceptability of unilateral extraterritorial sanctions as a foreign policy tool has been and remains the core of our position. We see that Washington respects no limits in the pursuit of exerting pressure on countries it dislikes, including Iran," he added.

This undated photo by Iran's Tasnim news agency shows Russian Deputy Foreign Minister Sergei Ryabkov.

The sanctions also target Iran Tractor Manufacturing Co, the Middle East's largest tractor manufacturer, and Esfahan's Mobarakeh Steel Co, the largest steelmaker in the Middle East and North Africa region.

The Treasury’s announcement came two weeks before the Trump administration imposes a second round of sanctions, targeting Iran’s oil sector and banking, on November 4.

The first round of the sanctions, targeting Iran's access to the US dollar, metals trading, coal, industrial software, and auto sector, took effect in August.

Years of Western sanctions have hurt the Russian economy. US Congress is considering expanding sanctions on Russia’s big state banks, with an American business group warning on Tuesday that it could cause major turmoil for global energy supplies.

State banks dominate the Russian financial sector and work closely with energy giants in the world’s largest oil and gas exporter.

Alexis Rodzianko, president of the American Chamber of Commerce in Russia, told Bloomberg that hitting the banks would be “a scorched-earth approach to diplomacy”.

The Wall Street Journal, however, said US sanctions have driven the price of oil and the ruble apart, leaving Russia with expensive crude and a cheaper currency, a combination that is helping its economy.