MSCI's broadest index of Asia-Pacific shares outside Japan slipped 0.2 per cent, on track for a second straight day of losses.
It is down more than 4 per cent in February after global equity markets were mauled at the start of the month by worries US inflation is picking up.
Japan's Nikkei eased 0.2 per cent while South Korea's KOSPI index ticked higher. Australian shares slipped 0.4 per cent.
Jerome Powell noted in his semi-annual testimony on Tuesday that the US economy was strong, inflation was ticking higher and that the global backdrop was better than in December.
Asked about likely catalysts for more than three rate hikes in 2018, he said each member would write a new "dot plot" rate path ahead of the March meeting and that he wouldn't want to prejudge that outcome.
"These comments highlighted to market participants the possibility that, at the March meeting, the Fed's median "dot" could move up, signalling that four, rather than just three, hikes were likely to be appropriate in 2018," said Michelle Girard, chief US economist at NatWest Markets.
"While we believe the possibility exists that the median dot for 2018 moves higher, that is not yet our base case," Ms Girard added.
"Whether or not the median dot shifts, we are sticking with our long-held view that the Fed will hike rates four times in 2018."
Fears of faster US rate hikes have fed fears that other central banks will start to tighten policy and raise borrowing costs. That would in turn hurt corporate earnings, clouding the outlook for what had been expected to be another solid year of global economic growth.
The Fed had caused a so called "taper tantrum" in May 2013 when it signalled it was time to stop pumping cash into the US economy, a move that created havoc in financial markets -particularly in Asia.
Asian markets have, so far, taken US rate rises in their stride. The Fed moved three times in 2017 and is seen as certain to do the same or more this year, with the first move expected as early as March.
Rate futures fell following Mr Powell's remarks as traders began pricing in about a one-in-three chance of a fourth hike this year.
Equity markets in Europe and Wall Street turned south with the Dow, the S&P 500 and the Nasdaq falling more than 1 per cent each.
Bonds and currencies
Treasury prices slipped on Mr Powell's testimony with yields on the 10-year US note briefly rising past 2.9 per cent. They were last at 2.89 per cent.
The dollar staged a broad-based rally against most major currencies.
It rose 0.8 per cent overnight against the Australian dollar to hover near a recent one-and-a-half-month top.
Against the euro, it held near a three-week high after rising 0.7 per cent overnight. The euro was last at $1.2231.
The dollar's gains against the Japanese yen were, however, limited. It climbed 0.4 per cent overnight and was last up 0.1 per cent at 107.45 yen.
Commodities including base metals fell because a firmer dollar depreciates their value.
Oil fell amid expectations that upcoming weekly data will show an increase in US crude inventories.
Brent crude futures closed down $1.09 at $66.41 a barrel, while US crude was last down 22 cents at $62.79.
Spot gold slipped to $1,316.86 an ounce, not far from Tuesday's $1,313.26 which was the lowest in three weeks.