Schurrle said that his side were the better team for "more than an hour" and that they deserved at least a draw from the game.
"It's incredibly frustrating for us," he told Bundesliga.com. "We were the better team for more than an hour and had chances to score maybe five goals.
"If we'd played more intelligently, we could have got at least a draw out of it. We were on the crest of a wave and then that stupid thing happens."
Leverkusen are now third, two points behind Dortmund.