The United States has said it is determined to enforce a price cap on Russian oil announced by the G7 countries.

"A price cap on Russia oil is a powerful tool -- one part of the tool in our agenda to put downward pressure on global energy prices in a way that will benefit consumers in the US and globally," White House Press Secretary Karen Jean-Pierre told reporters during her daily news conference here Friday.

"And we are determined to implement this policy in a way that achieves those goals," she said.

Earlier in the day, G7 finance ministers announced a cap on the price of Russian oil, which they said would put pressure on global energy prices while denying Putin revenue to fund his brutal war in Ukraine.

As per the announcement, the G7 countries, along with other allies and partners, plan to prohibit the provision of services that enable maritime transportation of such oil and products unless purchased at or below a price level determined by the coalition of countries adhering to and implementing the price cap.

"By committing to finalise and implement a price cap, the G7 will significantly reduce Russia's main source of funding for its illegal war, while maintaining supplies to global energy markets by keeping Russian oil flowing at lower prices," US Treasury Secretary Janet Yellen said.

"While we have seen energy prices ease in the United States, energy costs remain a concern for Americans and continue to be elevated globally. This price cap is one of the most powerful tools we have to fight inflation and protect workers and businesses in the United States and globally from future price spikes caused by global disruptions," she said.

Responding to a question, Jean-Pierre told reporters that the impact of G7 efforts to implement a price cap is already bearing fruit.

"Reports show that Russia is already offering steep discounts -- as much as 30 per cent -- and long-term contracts to some countries. This also demonstrates that Russia is planning to continue supplying its oil and willing to swallow bigger discounts," she said.

"A price cap will give more countries better leverage to strike deals with Russia. We will further work in the coming weeks to determine the price cap level; release further information, including technical guidance for market participation; and announce our coalition partners as well," said the press secretary.