WASHINGTON -- US President Donald Trump said Sunday he may impose "secondary tariffs" on Russian oil if he believes Russia is at fault for not reaching a ceasefire with Ukraine.

In a phone interview with NBC News, Trump said he was "very angry" and "pissed off" when Russian President Vladimir Putin criticized the credibility of Ukrainian President Volodymyr Zelensky's leadership, adding that the comments were "not going in the right location."

"If Russia and I are unable to make a deal on stopping the bloodshed in Ukraine, and if I think it was Russia's fault -- which it might not be -- but if I think it was Russia's fault, I am going to put secondary tariffs on oil, on all oil coming out of Russia," Trump said.

"That would be that if you buy oil from Russia, you can't do business in the United States," he said. "There will be a 25 percent tariff on all oil, a 25- to 50-point tariff on all oil."

Trump noted that the tariffs on Russia would come within the next month if Moscow does not sign up to a ceasefire with Ukraine.

Trump said Putin knows he is angry, but he has "a very good relationship" with Putin and would speak to the Russian leader again this week.

During a phone conversation on March 18, Trump and Putin agreed that the peace in Ukraine "will begin with an energy and infrastructure ceasefire."