Srivastava was reported by on-field umpires Peter Hartley and Marais Erasmus, and third umpire Enamul Haque-Moni.
He was charged under Level 1.6 of the Code of Conduct which deals with pointing or gesturing towards the pavilion in an aggressive manner by a bowler or any other member of the fielding side upon the dismissal of a batsman.
The charge related to an incident during the New Zealand innings when Srivastava pointed towards the pavilion in an aggressive manner after dismissing Corey Anderson for 70 in the 49th over.
Srivastava pleaded guilty to the charge and he was given an official reprimand by ICC Match Referee Chris Broad.
Explaining his decision, Broad said,''I understand that in the heat of the moment young players can get excited, especially when they have just dismissed the opposition"s highest scorer. But it is important for them to realise that gesturing a batsman towards the pavilion in this fashion is disrespectful and is contrary to the spirit of the game.''
''This is Tanmay's first offence under the ICC Code of Conduct and as such I am happy with giving him an official reprimand. He needs to remember that this sort of behaviour is unacceptable from any player in the game no matter what his age and no matter what the circumstance,'' he added.
For Level 1 offences, there is no right of appeal and the Match Referee's decision is final.
India under-19 coach Dav Whatmore and team manager Gopal Bose were present along with Tanmay Srivastava at the hearing.