The police have cited the injunction presently in effect at the airport, and the increasingly violent civil unrest sweeping the city, in issuing a letter of objection against the Confederation of Trade Unions (CTU) on Monday evening, the South China Morning Post reported.
The city's Airport Authority had its injunction against protests extended last week. It obtained its injunction after a peaceful five-day sit-in turned ugly and resulted in the cancellation of 979 flights.
Citing the "general societal atmosphere", police were not convinced the CTU could control the behaviour of people taking part, or the safety of passers-by.
The CTU said that it wanted to hold the protest against the Hong Kong flag carrier's decision last week to fire the head of a cabin crew association.
"The CTU strongly condemns the police for jeopardising the freedom of assembly by citizens, and has immediately appealed to the Appeal Board on Public Meetings and Processions," veteran unionist and former lawmaker Lee Cheuk-yan said.
Cathay had earlier warned employees not to join the rally, which was a response to the abrupt dismissal of Rebecca Sy On-na, the head of the Hong Kong Dragon Airlines Flights Attendants' Association.
The airline has neither confirmed nor denied Sy's allegations that she was fired over a Facebook post.
( With inputs from IANS )