No deaths have been reported. It is also the most populous Muslim-majority country. The area is popular for diving and tourists.
The undersea quake hit at a depth of 24km at about 1.00am (1600 GMT), 30km from Sorong, in West Papua province, the US Geological Survey said.
No tsunami warning was given.
Indonesia is prone to earthquakes as it sits on a vulnerable quake-hit zone called “The Pacific Ring of Fire”.
The majority of the injuries were from broken bones or other less serious issues.
Hundreds of patients from at least one hospital in the city had to be evacuated, some in wheelchairs or with drips attached, said disaster official Burhanudin.
He said there were no immediate reports on casualties, and rescuers were still collecting data on damages.
Meanwhile, Indonesian news agency, Antara, reported that the natural disaster caused panic among residents in West Papua who left their houses seeking for safer ground.
The strong quake was similarly felt by people in Raja Ampat, which is northwest of the location of the epicenter. But he added there were no signs of damaged buildings or injured people.
The agency said initially that the magnitude was 6.9, but then geologists nudged it a bit lower.