Pujara, who suffered the injury during IPL 4 in which he was representing the Royal Challengers, Bangalore, underwent a surgery in London on 1 July and has been advised rest for three months after which he can resume his cricket practice.
He is currently undergoing rehabilitation at the National Cricket Academy in Bangalore.
'I suffered the tear in my anti-cruciate ligament during fielding. I was going through some rehab after the injury. We were not very sure whether its a complete tear because there was no pain.
'But then I went to London to consult a knee specialist on 28 June. He told me that I would have to undergo a surgery. I had suffered the same injury in my left knee during IPL 2,' he said.
'It will take me four months to recover, and three months before I can start practice,' he said.
The Saurashtra Ranji Trophy batsman said losing out opportunities due to injuries was disappointing.
'I'm defitinitely losing out opportunities but it is not in my hand because once you are injured you can't do anything. You are disappointed that when you want to play for the country you are out not because of selection but because of injury. I think you have to accept it.
'I take it in a positive way. You cannot change what has happened. There is no other option. So my aim is to look after my injury and get fit to play again,' he added.
Pujara, who has represented India in three Test matches scoring 107 runs in five innings, has received encouragement from opener Virender Sehwag, who too was at the NCA after his shoulder surgery, and senior batsman Rahul Dravid.
'Sehwag told me don't worry it will be ok. Whatever has happened has happened. Just focus on your rehab. Dravid sent me a message saying that 'don't worry you are injured but I'm very sure you will be able to come out of it',' he said.
Pujara, who scored a crucial attacking 72 against Australia in the fourth innings of his debut Test at Bangalore last year, felt he had done well in the limited opportunities he had got.
'Everyone appreciated my innings against Australia. Gary Kirsten and all senior players. Even the way I batted in South Africa, everyone was impressed with the way I was able to cope up with fast bowling in conditions where pace and bounce is more.
'In South Africa, I was at the crease in difficult conditions but had crucial partnerships with Laxman bhai in one match and Dhoni bhai in another which was important for the team. At that time even a 25-40 run partnership was important. So everyone appreciated that.
'Kirsten just told me to start converting my innings. 'When you get set you have to start scoring runs',' he said.