England are trailing 0-1 in the series after losing by 95 runs in the second Test at Lord's.
"We all need a kick up the backside sometimes," said Moores was quoted as saying by 'The Mirror'.
"If you think it's a wasted opportunity because people aren't trying, you're going to kick them up the backside - because they're not putting in," he said.
Moores said only those who are capable of coming good in tough circumstances deserve to stay in the team.
"We've got a clear picture of where we're trying to get to. We want to play in a way people will be proud of. As selectors, we've got to pick the guys we think can achieve that," he said.
"I thought Moeen (Ali) had his best game with the ball and he is improving all the time. We've lost some key players including our spinner and it takes time for that to be developed.