The notice said: "At this stage, we do not believe that customer and employee data has been compromised."
Toyota said it had set up an emergency call centre to handle customer inquiries about the recall of Takata airbags.
This would be in operation on 23 February, and operate from 9am to 6pm on 1800 462 000 until further notice.
"We will advise once normal customer operations through the Guest Experience Centre are restored," Toyota said on its website.
"Customers calling the emergency number will be requested to provide their best contact details, the name of their closest/preferred dealership and their vehicle information, including VIN and registration.
"We apologise for any inconvenience and continue to thank customers for their patience as we work towards resolving the situation."
News of the Toyota attack came on the same day that the Melbourne Heart Group was revealed as being the victim of a Windows ransomware attack.