The Saints must now score four goals in Germany if they are to progress to the next stage of the competition.
Speaking to the Irish Times, Buckley said: “It’s quite a tough one, we’re disappointed with the scoreline.
"The second goal took stuffing out of us because up to then in the the second half we were having a go at it but to lose that second goal took the wind out of our sails and the third goal was poor."
He continued: “But they are a top team, full of internationals. We played well in the first half without creating much while their first goal was great.
“At half-time I said that we could do better and I would have expected a bit more from our lads," added the Saints boss.
"It was a big night for them all and I don’t think they did themselves justice which is disappointing."
With the second leg in Hannover seeming like a daunting prospect after the defeat, Buckley says that his team must nevertheless play with pride.
“We play with pride like we have done all season," he said. "And look to see where we can improve and tighten up; they are a quality side.”
St Patrick's Athletic travel to Germany to take on Hannover 96 in the second leg of the Uefa Europa League Third Qualifying round on Thursday August 9.
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