Benchmark copper slipped 0.2 percent to $6,126 per tonne by 1054 GMT, on course to end the week about 3 percent lower.
US companies likely maintained a strong pace of hiring in July, suggesting that the robust economy was helping the labour market to weather trade tensions, according to a Reuters survey of economists.
"After the surprisingly positive ADP report two days ago, we might get quite positive official data today. That's why the dollar is firmer and therefore weighing on metals," said Commerzbank analyst Daniel Briesemann.
There were fears that trade tensions between the world's two largest economies would escalate after China vowed to retaliate if the United States acted on a threat to raise tariffs on the Asian nation's exports, adding further pressure on metals.
"Behind the weakness in metals prices is the trade dispute between the US and China where more fuel was added to the fire overnight," Briesemann said.
The ADP National Employment Report showed private payrolls surged by 219,000 jobs in July after rising by 181,000 in June, helping support expectations for solid job gains in July.
DOLLAR: The dollar index firmed for a fourth straight day, making assets priced in the greenback, such as copper, more expensive for holders of other currencies.
STRIKE: The threat of a major supply stoppage lingered after the union at BHP Billiton's Escondida mine in Chile, the world's biggest copper mine, told the company on Thursday that it should improve its contract offer by August 6 or it would begin preparations for a strike.
STOCKS: Headline stocks in copper fell 825 tonnes to 250,625 tonnes. Headline stocks have shed 35 percent since late March to the lowest since Jan. 22.
CHINA: China is considering measures to curb pollution in its smog prone Beijing-Tianjin-Hebei region and nearby areas during the upcoming winter season, including 30 percent production cuts on non-ferrous metal smelting, a draft plan showed on Thursday.
ALUMINA: The city of Chaoyang in China's northeastern province of Liaoning says it has cancelled a planned alumina project after a public consultation.
OTHER METALS: Aluminium shed 0.4 percent to $2,027 per tonne, on track to end the week 2 percent lower. Lead was steady at $2,116, tin fell 0.5 percent to $19,510, zinc added 0.5 percent to $2,576 while nickel shed 1.3 percent to $13,160.