U.S. West Texas Intermediate crude futures settled 4 cents lower at $61.66, having earlier hit $62.49. WTI ended the week down about half a percent.
Brent crude oil was up 23 cents at $70.62 a barrel, having touched a peak of $71.23. Brent ended the week slightly lower.
Futures chalked up the weekly losses during volatile week with investors worried over the possibility of a protracted and bitter U.S.-China trade war, despite last-minute efforts to salvage a deal.
President Donald Trump ordered the tariff increase, saying China "broke the deal" by reneging on previous commitments. He said he would start paperwork for 25% duties on a further $325 billion of Chinese imports, saying he was in no rush for a deal.
Growing trade between the world's two largest oil consumers could affect oil demand. The United States and China together accounted for 34% of global oil consumption in the first quarter of 2019, data from the International Energy Agency shows.
But investors shifted their focus away from trade issues to the impact of Iran sanctions, as well as conflicts in Libya that threatened oil supplies, said Gene McGillian, vice president of market research at Tradition Energy in Stamford, Connecticut.
"The market continues to show concern about tightness of supply," McGillian said.
"We're close to summer driving season and so far the Saudis and the Russians don't want to raise production, and Iran sanctions are in place," said Dan Flynn, an oil trader and analyst at Price Futures Group in Chicago. "That's supportive of crude prices."
Washington is seeking to cut Iran's oil exports to zero. The United States reimposed sanctions on Iran in November after pulling out of a 2015 nuclear accord between Tehran and world powers last year.
It initially allowed Iran's biggest buyers to continue purchasing oil via waivers for another six months, but those exemptions ended at the beginning of May.