The euro strengthened to $1.3007 against $1.2986 in New York Trade late Thursday, but the greenback plugged its descent against the Japanese currency at 77.55 yen from 77.48 yen in US trade.
The European common currency bought 100.88 yen in Tokyo morning trade against 100.61 yen in New York.
On Thursday, the US Federal Reserve said it would unleash a new, open-ended $40-billion per month asset purchase programme, pumping more money into the economy to keep interest rates low and spur lending and investment.
The Fed said the new monetary easing would remain in place until it saw substantial improvement in the US jobs market, where 8.1 percent of Americans remain unemployed.
"It was an aggressive additional easing that ignores the current inflation pressure," Credit Suisse analyst Hiromichi Shirakawa said.
Shirakawa added that the move heaped pressure on the Bank of Japan (BoJ) to announce its own easing measures as a strong yen and weakening overseas export demand weighs on the world's third-largest economy.
The Japanese central bank is expected to expand its 70-trillion-yen ($900-billion) asset purchase programme by about 10 trillion yen at a meeting in late October at the latest, he said.
The dollar's weakness against the Japanese unit -- it hit a seven-month low of 77.13 yen on Thursday in New York -- prompted Finance Minister Jun Azumi on Friday to repeat warnings over market intervention to stem the yen's rise.
Reports that the central bank carried out a rate check with several banks during New York trading hours, the first since early June, was the strongest signal yet that Japanese officials would step into forex markets.
The yen hit record post-war highs around 75 against the dollar late last year and remains strong.
A landmark ruling by a German court on Wednesday overturned a raft of legal challenges and cleared the way for the eurozone's permanent bailout fund -- the European Stability Mechanism (ESM) -- to come into effect.
With the 500-billion-euro fund in place, fears about fiscal turmoil in debt-battered Europe have eased, giving support to the euro.