The tiger reached the other side of the river unharmed, an official said.
A Royal Bengal Tiger was filmed swimming across a river in the Sunderban National Park when a trawler of fishermen drove straight towards it. As the trawler reached close to the tiger, the big cat turned around and tried to attack the boat. The fishermen could then be seen prodding at the tiger with a long wooden stick.
Authorities at Sunderban Tiger Reserve said they received the video footage on Friday and are trying to track down the men. The tiger reached the other side of the river unharmed, an official said, adding that they will be taking necessary action against the fishermen.
"As can be seen, the tiger is trying to cross the river in Sunderbans and, in no way, it threatened the lives of the fishermen on the trawler," Sunderban Tiger Reserve Field Director Nilanjan Mullick told NDTV. "On the contrary, the fishermen on the trawler tried to disturb this particular animal while it was swimming," he said.
"This is clearly against the law and we're trying to obtain information regarding the owner of trawler and the fishermen. After receiving all the information, we will file a case against those people under the provisions of the Wildlife Act," Mr Mullick said.
Sunderban Tiger Reserve is the largest tiger reserve in the country and the only mangrove forest in the world with tiger as its indigenous population. The tiger reserve has about 80 tigers. Also, Royal Bengal Tiger is accorded the highest legal protection under the Wildlife (Protection) Act.
From an estimated 100,000 tigers at the beginning of the 20th century, India saw the numbers dropping to 1411 in 2008. Most of the animals were killed by poachers who sell the carcasses for use in traditional Chinese medicine. However, by 2015, the number of tigers in India saw a sharp rise to 2,226 tigers from 1,411 seven years ago.