"We would like to reinstate services, but it's just too late. You can't just turn an airline on and off," Qantas spokeswoman Olivia Wirth said.
Qantas had already already published a new flight schedule, which included 17 cancelled flights and 29 delayed flights, she said.
The flight changes are expected to affect more than 5700 passengers.
"Customers are already being contacted alerting them to changes to their flights, planes have been changed and repositioned, and employees including pilots and cabin crew have been redeployed," Qantas said in a statement.
"We have also notified air traffic control of the new schedule."
Meanwhile, members of the Australian Licensed Aircraft Engineers Association (ALAEA) are pushing ahead with plans for a one-hour work stoppage at Melbourne Airport from 3pm on Friday, which will probably cause some minor delays.
In better news for travellers, Qantas says it has reached a new enterprise bargaining agreement with the union representing its short-haul cabin crew.
The agreement with the Flight Attendants Association of Australia would go to a vote in about three weeks, the airline said.
The three-year agreement includes a three per cent pay increase each year as well as an annual $500 lump-sum payment.
- AAP