MELBOURNE—The Australian government responded to tennis star Novak Djokovic’s assertion that he was assured entry with a medical exemption from coronavirus vaccine requirements, pointing out in court papers filed Sunday that no foreigner has a guaranteed right to enter the country. “There is no such thing as an assurance of entry by a non-citizen into Australia. Rather, there are criteria and conditions for entry, and reasons for refusal or cancellation of a visa,” the government said in a filing ahead of a court hearing on the case on Monday. Djokovic, the world number one, is hoping to win his 21st Grand Slam at the Australian Open, which starts in Melbourne on Jan. 17. But instead of training, the Serbian player has been confined in a hotel used for asylum seekers and is challenging the decision to cancel his visa after being stopped on arrival at Melbourne Airport early on Thursday. …