After a string of below par performances, Dinesh Karthik handed over the reins to his deputy Eoin Morgan hours before KKR's match against Mumbai Indians on Friday.
Rohit Sharma had clocked in his 150th appearance for the franchise during the side's game against Delhi Capitals at the Sheikh Zayed Stadium in Abu Dhabi.
The IPL release said: "The report was made by the on-field umpires according to the IPL's Suspected Illegal Bowling Action Policy. Narine will be placed on the warning list and is permitted to continue to bowl in the tournament.
The Rohit Sharma-led team scored 193 runs after opting to bat first. Jasprit Bumrah took four wickets while James Pattinson and Trent Boult picked two wickets each in the match as Rajasthan Royals were all out on 136 runs.
Suryakumar and Hardik Pandya smashed 19 runs in the 18th over and 17 in the final over to get past 190 run mark. The highlights of the game were Suryakumar's scoop shots that went for fours and six in the death overs.
On Thursday evening, Agarwal scored 25 off 18 balls which took his tournament tally to 246 runs from four games and he is now at the top of the list of leading run scorers. Rahul, who managed 17 against Mumbai during Kings XI's chase of 192
A late onslaught by Hardik and Pollard powered Mumbai Indians to post a mammoth total of 191 runs. Mumbai defeated KXIP by 48 runs on the back of an all-round bowling performance.
James Pattinson, Jasprit Bumrah