The Chinese nationals entered Vietnam on tourist visas and had been working for the company Nature Love as accountants and tour guides, Tran Chi Cuong, deputy head of the Tourism Department, told local media.
Each of them was fined VND20 million, or around US$900.
Earlier this month the city had fined six other Chinese nationals for similar violations.
Last week the Vietnam National Administration of Tourism called on Danang authorities to check the operations of all travel agents and expel illegal Chinese tour guides following accusations that they distorted Vietnamese history while showing tourists around.
The violators could also face a ban on entering Vietnam ever again.