The Blaugrana stand-in boss is adamant that their impending European clash had no effect on their performance on Saturday
The Blaugrana face the Ligue 1 leaders at Parc des Princes on Tuesday in the first-leg of their quarter-final draw, and a number of key faces - such as Andres Iniesta and Carles Puyol - were rested from the starting line-up.
However, Roura rejected suggestions that his side had one eye on their European encounter against the Primera Division strugglers.
"Tuesday is an important game, but we did not have our heads in Paris. We knew [the match against Celta] was going to be difficult," the club's official website quotes the coach as saying.
"We dominated the second half, but this is football. We gave everything, but in the end we just couldn't do it."
Barca starlet Marc Bartra was given a rare start in defence and the 22-year-old was thankful to centre-back Gerard Pique for his guidance throughout the Celta game, and looked ahead to their tie with Carlo Ancelotti's men in midweek.
"Pique has helped me a lot, he’s a leader for me and we understand each other well when we play together," he said. "It’s important to get more playing time. I was more comfortable in the second half.
"We knew that Celta had won most of their points this season at home and that they’d make it difficult for us.
"Now it’s time to think about the match in Paris. We need to move on from today’s game, and hopefully everything will work out well."
Barca are 13 points ahead of Real Madrid with nine games to play in La Liga and are looking increasingly likely to reclaim the title which Jose Mourinho's side took from them last season.