Vishal, the 10-year-old white tiger, has so far spurned the advances of tigress Rupa, living in the adjoining enclosure, an official told the BBC.
Libido enhancers have also failed to spur him into action, he said.
Experts blame his "shyness" on the fact that Vishal has been bred in captivity.
"For the past six months we've been trying to mate Vishal," Dayanarayan Banerjee, who retired as the senior veterinary officer at the zoo and is now working as a veterinary consultant there, told the BBC.
"We have de-wormed him to improve his overall health. We have given him libido enhancers, including vitamin D, A and E. But he is shy and no libido has been noticed in him," he said.
Mr Banerjee says this is the first time an attempt has been made to mate Vishal - the only male in the breeding age in the zoo - but perhaps he is a bit too old to mate.
"The most suitable age for a tiger to mate is when he is five-six years old. Seven-eight-year-olds also succeed. But beyond the age of 10 years, it is very difficult."
Mr Banerjee said when Vishal was introduced to eight-year-old Rupa, he was "friendly enough" and "displayed no sign of hostility", but that's where the contact ended.
"Rupa was willing, but Vishal was reluctant," he added.
Mr Banerjee says he is "not sure Vishal will deliver" but zoo authorities are not yet giving up on the exercise.
"We are considering introducing him to Rani, she is a Bengal tigress, and she has a very beautiful face. But she is in an enclosure that's far away from Vishal's and we are awaiting a decision on whether we can move her to a nearby enclosure."
Officials at the Alipore zoo in the Indian city of Kolkata (Calcutta) say their attempts to mate a young tiger have been unsuccessful with the big cat showing little interest in mating.