The Irish official showed a red card to Welsh captain Sam Warburton in the 18th minute for a tackle which lifted France winger Vincent Clerc off the ground.
Wales battled gamely in the second half - and had chances to win the game, missing 11 points' worth of kicks at goal - but Gatland felt Rolland's decision had proved crucial.
"We just feel like the destiny of the result was taken out of our hands with the red card," he told ITV1 after the 9-8 defeat.
"He's lifted him, that's a yellow card, but he's not driven him into the ground. Does that mean every time there's a tackle where you lift someone off the ground it's a red card?
"Why spoil the semi-final with a red card? He's not a dirty player. I'm just gutted.
"We were down to 14 but we showed great character and I'm proud of our efforts. But we can't go to just one tournament and do well, we've got to kick on from here.
"I feel let down, I thought this team were good enough to go on and take the final but it was not to be. We just feel that ultimately the result wasn't in our control."
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