Rohit Sharma credited the top order batsmen for the 18-run win over Royal Challengers Bangalore.
Kohli said his team needed to work on lot of areas including bowling and approach to batting.
Harbhajan Singh was awarded man of the match for claiming three wickets for 27 runs.
MI recorded their first victory in the IPL 2015 by beating RCB by 18 runs.
Mumbai have been searching for the right combination at the top of the order.
While RCB have at least won a game in the two they have played, MI are yet to win a game, having lost four in four.