The United States says it wants to reduce oil exports from Iran, the world's fifth biggest oil producer, to zero by November, in a move that will oblige other big producers such as Saudi Arabia to pump more.
If Beijing does impose tariffs on American oil, it could put downward pressure on the price of West Texas Intermediate crude, the US benchmark, and may weaken its spread to Brent oil, the global market standard.
Meanwhile, Brent oil price was under pressure on Friday amid an escalating global trade tensions. It estimated that once US sanctions are fully implemented, some 1.7 to 2 million bpd of crude and condensate would be taken out of the market.
Benchmark Brent LCOc1 was up 40 cents at $77.51 a barrel by 0850 GMT.
Crude Oil WTI futures for delivery in August traded at $74.8 per barrel, or 0.38 percent higher from their previous close.
The US ships about 400,000 barrels a day of crude to China, worth $1bn a month at current prices. "They (Chinese importers) are not going to be intimidated, or swayed by US sanctions", he said.
It shows the year-on-year percentage growth in U.S. non-farm payrolls, splitting the results by oil and non-oil producing states.
As part of the retaliatory response, Beijing has threatened a 25 percent tariff on USA crude imports, although it has not specified an introduction date.
An executive from China's Dongming Petrochemical Group said he expected Beijing to soon impose the tariff on US oil imports.
The potential trade war between the United States and China comes amid a tight oil market.
A Chinese import tariff would make USA oil uncompetitive in China, forcing its refiners to seek alternative supplies in a tight market.
Energy consultancy FGE this week issued a stark warning of looming supply shortages due to USA sanctions against Iran and also because of disruptions elsewhere. By some estimates, about 1.7 to 2 million bpd of crude and condensate would be cut out of markets once the sanctions are implemented.
USA investment bank Jefferies said on Friday it expected a drop in Iranian exports well in excess of 1 million bpd due to the US sanctions.
Most Indian refineries are created to process heavy, high-sulphur Iranian crude while bulk of the growth in American supply has been in light, low-sulphur oil produced in shale developments.
The Korean government, the sources said, had pressured refiners into suspending orders for July shipments of Iranian crude, which is the first time this has happened since 2012, Reuters notes.
Top exporter Saudi Arabia told OPEC it raised oil output by nearly 500,000 barrels per day last month, OPEC sources said, a sign Riyadh wants to make up for shortages elsewhere and dampen prices.