The U.S. central bank announced on Wednesday that it would spend $600bn to buy government bonds, in the hope that the cash injection can kickstart the country's economy.
However, this weakens the dollar, making imports from around the world more expensive for U.S. consumers.
German Finance Minister Wolfgang Schaeuble said the U.S. policy was "clueless" and would create "extra problems for the world."
China's Central Bank head Zhou Xiaochuan urged global currency reforms, while South Africa said developing countries would suffer most.
The U.S. policy "undermines the spirit of multilateral co-operation that G20 leaders have fought so hard to maintain during the current crisis," South Africa's finance minister Pravin Gordhan said.
The heads of state and government of the G20 group of the world's leading nations is due to meet in a week in South Korea, with currencies and trade imbalances high on the agenda.
"If the domestic policy is optimal policy for the United States alone, but at the same time it is not an optimal policy for the world, it may bring a lot of negative impact to the world," said Mr Zhou.
Germany's finance minister Wolfgang Schaeuble said on German television that "with all due respect, U.S. policy is clueless."
"It is not that the Americans have not pumped enough liquidity into the market and now to say let's pump more into the market is not going to solve their problems."
He added that the German government was going to hold bilateral talks with U.S. officials and discuss the topic at the G20 summit in Seoul next week.