Tamil Nadu topped the league and finished with 23 points to qualify for the knock-out round to be played at Mumbai.
The match was reduced to 44 overs due to wet pitch on account of dew.
Kerala, who batted first after winning the toss, failed to come to terms with the Tamil Nadu bowlers as they could score just 207 runs by losing eight wickets in their allotted 44 overs.
Opener V A Jagdish, who remained not out on 73, took the fight to the rival camp along with K Chandrashekar (48) as they shared a seventh wicket partnership of 87 runs to help Kerala cross the 200-mark.
M R Srinivas and R jesuraj claimed two wickets each for Tamil Nadu.
In reply, opener Vidyut Sivaramakrishnan scored 59 and shared a third wicket partnership with Badrinath (67). S Sarath (37) also supported well.
For Kerala, Tinu Yohanan scalped two wickets while Sreeshanth chipped in with one wicket.
Brief Scores: Kerala 207 for 8 in 44 overs (V A Jagdish not out 73, K Chandrashekhar 48, M R Srinivas 2-46, R Jesuraj 2-46) lost to Tamil Nadu 212 for 3 in 37.2 overs (V Sivaramakrishnan 59, S Badrinath 67, S Sarath not out 38), T Yohanan 2-48).