In Europe, Germany's DAX rose 0.6% to 12,188 and Britain's FTSE 100 rose 0.3% to 7,386.
The S&P 500 index eased 0.2% to 2,879.84 and the Dow Jones Industrial Average also fell 0.2% to 26,004.83.
The demonstrations snarled traffic and delayed a legislative debate on a bill that would allow criminal suspects in Hong Kong to be sent for trial in mainland China, a proposal that is sharpening fears over growing Chinese control and an erosion of civil liberties in the semiautonomous territory.
The crowds overflowed onto a major downtown road as they overturned barriers and tussled with police, who used multiple rounds of tear gas and threatened to use more forceful measures if necessary.
Major thoroughfares were blocked by the protests as lawmakers prepared to debate the bill, which would allow extraditions to China and that many fear will hammer Hong Kong's reputation as an global business hub.
Japan's Nikkei 225 index lost 0.4% to 21,129.72 and the Kospi in Seoul shed 0.1% to 2,108.75. The Shanghai Composite index added 0.1% to 2,910.74. Australia's S&P ASX 200 was less than 0.1% lower at 6,542.40, even after the release of better-than-expected jobs data. Investors were anxious that a trade dispute between the world's two largest economies would drag on for longer than expected.
Hopes that the leaders of the two countries will clinch a deal on the sideline of Group of 20 summit meeting in Osaka on June 28-29 have been fading as neither side has shown a willingness to compromise.
"I think in order to see the dollar weaken further, you need to see some follow through from the Fed on rate easing", said Mazen Issa, senior FX strategist at TD Securities in NY. "And we're either going to do a great deal with China or we're not doing a deal at all".
The yield on the 10-year Treasury has dropped from around 2.50% in early May to 2.12% Wednesday.
ENERGY: Benchmark U.S. crude lost 9 cents to $51.05 per barrel in electronic trading on the New York Mercantile Exchange. It rose 1 cent to $53.27 a barrel on Tuesday.
In currencies, the US dollar was little changed against the euro as investors were slow to take large positions before the Fed meeting and the G20 summit later in June when USA and China leaders are expected to discuss trade.
The euro stood little changed at $1.1293, having taken a hit on Wednesday after US President Donald Trump said he was considering sanctions over Russia's Nord Stream 2 natural gas pipeline project and warned Germany against being dependent on Russian Federation for energy.