Replying to Mumbai Indians' 173/5, KKR ended at 164/8, to miss out on the second spot in the table.
"With the kind of wicket this was, this was chaseable. Had one of the batsmen batted till the end, we would've got there. Just irresponsible shots, batsmen were trying to throw their bats at everything...
I thought we were trying to chase this down on 10-12 overs," Gambhir said after the Eden Gardens game.
However, he commended the KKR bowlers for restricting Mumbai to 173, calling it "an unbelievable effort".
Gambhir also conceded that his team was a batsman short. He said KKR needed to pull up their socks.
"If we bat like this it doesn't matter if we're in the Playoffs or not. Got to bat better."