The rally, held under the theme of "Evoke termination, stop terrorizing CX staffs" and organized by the Confederation of Trade Unions (HKCTU), was prompted by the sudden dismissal of Rebecca Sy, head of Cathay Dragon's Airlines Flight Attendants' Association.
The protest was scheduled to take place in front of the headquarters of Cathay Pacific near Hong Kong International Airport, but it was banned by the police and HKCTU decided to hold a gathering in a public square in Central instead, Efe news reported.
Sy, who had been with Cathay for the last 17 years, said she was fired without explanation after managers confirmed posts on her Facebook account related to the recent wave of anti-government protests. The airline has not denied nor confirmed she was fired over her comments on the social network.
Cathay warned its employees last week that everything they publish on social networks would be "subject to intense scrutiny" and that those who express their support for the protests, triggered by the government's controversial extradition bill, could be victims of "a new policy" imposed on the airline by the aviation authority of China.
Some Hongkongers have take to social media to demand that the company reinstates Sy and explains the reasons for the dismissal, requests that were repeated during Wednesday's march.
Sy's sacking came a week after the shock resignation of Rupert Hogg, Chief Executive of Cathay.
The company has been caught in the crossfire of Hong Kong's worst political crisis in decades.
China's aviation regulator recently told Cathay to suspend staff from flying over its airspace if they were involved in or supported the demonstrations. At least 20 pilots and cabin crew have since been fired, the HKCTU said.
In a separate event, hundreds of people gathered at a park in Central on Wednesday to protest against the alleged abuse of arrested female protesters by police officers.
( With inputs from IANS )