Australian Immigration Minister Alex Hawke made the ruling early Friday morning ... revoking the 34-year-old's visa just days after a judge had allowed the tennis star to go free in the country.

In announcing his decision, Hawke explained pulling Djokovic was in the best for "public interest" ... due to the athlete's COVID-19 vaccination status and controversial claims to a vaccine exemption.

"In making this decision, I carefully considered information provided to me by the Department of Home Affairs, the Australian Border Force and Mr. Djokovic," Hawke said.

"The Morrison Government is firmly committed to protecting Australia's borders, particularly in relation to the COVID-19 pandemic."

Djokovic has already started the process of an appeal -- and it's possible he could play in the opening round of the Australian Open on Monday while the arguments play out in court.

Australia's Prime Minister, Scott Morrison, meanwhile, backed Hawke's decision Friday ... writing in a statement, "Australians have made many sacrifices during this pandemic, and they rightly expect the result of those sacrifices to be protected."

"This is what the Minister is doing in taking this action today."

If ultimately deported, Djokovic could face a 3-year ban from the country.