"Personally I'm against vaccination. I wouldn't like that someone forces me to get a vaccine in order to be able to travel," the world number one said late Sunday.
The Serbian star was speaking from Spain, where he is in lockdown with his family, in a video conference held on his Facebook for Orthodox Easter.
"We (players) will have to travel. I think it will be the number one challenge," the 32-year said.
"If it (vaccination) will become compulsory what will happen? I will have to take a decision," on whether to get a vaccine or not, he said.
"This is my opinion at the moment. Whether it will change I don't know."
There is currently no vaccine for the virus that has claimed some 165,000 lives around the globe, though labs around the world are racing to develop a treatment.
Like the rest of the sporting world, tennis has been on pause since early March, with the ATP and WTA Tours suspended until mid-July at the earliest and Wimbledon cancelled for the first time since World War II.
Djokovic estimated tournaments would not restart "before September or October".
"The season will officially restart when everyone will be 100 percent certain that people can return, that there is no risk, that people are resistant to the virus and this takes time."
Tournaments with travel limited to one country or a region could be possible, he said. (AFP) ATKATK