This is stated on the website of the Russian Foreign Ministry.
The Ministry said that the decision was made in response to the Australian government's "politically motivated sanctions" against Russian individuals and legal entities. The Russian Foreign Ministry emphasizes that the restrictions are imposed as part of the Russophobic campaign of the 'collective West'.
The entry ban was introduced on an indefinite basis. At the same time, the Russian Foreign Ministry said that work on updating the Russian Federation's 'stop list' will continue, as Australia “does not intend to abandon its anti-Russian course and continues to introduce new sanctions measures.”