"We are disappointed and not angry with our performance from the boys, I think the performance is enough to win it," said the German, who has transformed Chelsea's season since taking over from Frank Lampard in January.
"I think today we were unlucky and we've never hidden that we need to have that to win at this level. You need momentum, decision making, little details, the referee," the German said.
Chelsea had a late potential equaliser ruled out for offside and some of their players also felt that Leicester's Ayoze Perez had handled before Youri Tieleman's stunning 63rd-minute winning goal.
"I didn't see it. My assistant saw it on the screen on the bench and the players said it straight away that is was a handball," said Tuchel.
"I think we defended well, counter-pressed well, didn't allow counter-attacks by one of the best counter-attacking sides in Europe," he said.
But he was less pleased with the way his team failed to make the most of their dominance of possession.
"Our decision making in the first half was too hectic, we tried to force the solution. We created two against two and three against three situations that were more promising than we made of it," he said.
"We conceded a goal from nothing. It's a fantastic goal and a lucky goal. We have a chance from Mason Mount, an offside goal that was very close. We were unlucky today," he concluded.
Chelsea face Leicester again on Tuesday in a key Premier League game in the battle to finish in the top four.
The London club face Manchester City in the Champions League final on May 29 in Porto.