The plane - which had 284 people on board - was travelling from Vancouver to Sydney on Thursday but had to be diverted to Hawaii.
Medical staff examined the injured after it landed at Honolulu's airport at 06:46 local time (16:46 GMT).
The Boeing 777-200 jet "encountered sudden clear air turbulence... two hours past Hawaii", the airline said.
It added that it was arranging hotels in Honolulu until a new flight to Australia could be arranged.
"We hit turbulence and we all hit the roof, and everything fell down... people went flying," Jess Smith, a passenger on board the flight, told local TV station KHON.
"Some people that weren't strapped in, you saw them rise in the air and hit their heads on the roof and everything, so it was quite intense," another passenger told the station.
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