The Treasury Department said it was prepared to take further action as it called on Moscow to agree immediately to a ceasefire in Russia's war in Ukraine, which began in February 2022.
"Given President Putin's refusal to end this senseless war, Treasury is sanctioning Russia's two largest oil companies that fund the Kremlin's war machine," Treasury Secretary Scott Bessent said in a statement.
"We encourage our allies to join us in and adhere to these sanctions."
The sanctions are a major policy shift for Trump, who had not put sanctions on Russia over the war and instead relied on trade measures. Trump imposed additional 25 per cent tariffs on goods from India in retaliation for it purchasing discounted Russian oil.
Trump has not imposed such measures on China, another major buyer of Russian oil. A $US60 ($A92) price cap on Russian oil imposed by Western countries after Russia's invasion has shifted Russia's oil customers in recent years from Europe to Asia.
Trump's measure on Wednesday followed Britain's sanctioning of Rosneft and Lukoil last week.
The Russian embassy in Washington and the Russian mission to the United Nations in New York did not immediately respond to a request for comment on the sanctions.
Meanwhile, Sweden signed a letter of intent to supply up to 150 of its domestically produced Gripen fighter jets to Ukraine, Swedish Prime Minister Ulf Kristersson said after meeting Ukrainian President Volodymyr Zelenskiy.
The two leaders met for talks in Linkoping in southern Sweden and visited Saab, which is the maker of the JAS 39 Gripen fighter, the GlobalEye surveillance aircraft, missile systems, anti-tank infantry weapons and other equipment.
Kristersson told a news conference the two countries had signed a long-term co-operation agreement over air defences.
The co-operation included the possibility of exporting 100 to 150 new Gripen E fighter jets in what would easily be Sweden's biggest ever aircraft export order.
"We fully realise it's a long road ahead of us," Kristersson said with a Gripen in Swedish livery in the background.
"But from today we are committed to exploring all the possibilities in providing Ukraine with a large amount of Gripen fighters in the future."
Ukrainian pilots have been in Sweden to test the Gripen and help smooth any eventual export of the jets, a rugged and relatively low-cost option compared to aircraft such as the US F-35.
Zelenskiy said Ukraine aimed to receive and start using Swedish Gripen jets next year.
"For our army, Gripens are a priority. It is about money, about manoeuvres," he told the press conference.
Kristersson said that nothing was decided yet but estimated that production and delivery of the first new aircraft could take three years.
The Gripen has been in commission since 1996 and Saab has produced about 280 of the planes in total.
Sweden has ordered 60 of the latest Gripen E model and Saab is increasing capacity in Linkoping, aiming to be able to produce 20-30 planes per year at the plant in a couple of years.
