Air-traffic controllers were to begin rolling 24-hour strikes on Sunday, with the action expected to ground flights on Monday, Wednesday and Thursday.
Passengers scheduled to travel should contact their airlines.
The action is being held in protest at a new law overhauling the Civil Aviation Authority, one of several reforms pledged by the government to international creditors.
The air-traffic controllers are demanding that some articles of the law, which also foresees the creation of a civil aviation agency that will act as a watchdog and deal with regulatory issues, be revoked.
Both the Civil Aviation Authority and the new agency will be under state control despite the initial insistence of creditors that they be made independent.
On occasion, Greek courts have stepped in to prevent prolonged or sudden strikes by air-traffic controllers, citing reasons of national security.