Spurs were beaten 2-1 by the French club in their opening Champions League fixture at Wembley in what was a disappointing result in front of a English club record crowd of more than 85,000.
Erik Lamela's pass was closed down by Fabinho allowing Bernardo Silva to drive into the area and fire home in the 15th minute before Thomas Lemar was able to lash home form the edge of the six-yard box after the Spurs defence failed to clear a Djibril Sidibe cross, prompting the following reaction from Pochettino.
"You pay when you make mistakes and we paid," he said.
"They only had two shots and like to counter. We created chances but weren't clinical.
"We must learn and improve. Today was a fantastic day to share with our fans but I feel very disappointed.
"We need to look at ourselves and criticise ourselves because it was our mistakes. We need to be more aggressive in front of goal."
"It's only the first game but we need to improve and fast. We need to play with more hunger and passion."
Spurs pulled one back through Toby Alderweireld's emphatic header from a Lamela corner on the stroke of half-time but were unable to find an equaliser during the second half.