The in-form Bees won 3-0 thanks to goals from Yehor Yarmoliuk and a double from Igor Thiago.
Speaking post-match, Le Bris said: “It is a tough place to come.
“I want to say well done to Brentford because they were very good, and we knew beforehand how difficult it would be.
“We didn’t start the game very well, but at the beginning of the second half we had an opportunity to get back into the game and we missed it. That moment was probably like conceding a second goal in itself because the energy in the stadium was high, and it felt like the beginning of the end for us.
“The penalty miss was probably the main turning point in the game. Today, Brentford were better than us.
“It is important to repeat that we lose as a team,” he continued. “We have done well so far, but we have to accept defeat when it comes like this. We were not at the required level tonight and we were punished.
“The penalty was an important moment because they are a strong team. We showed good energy at the start of the second half, but we missed the opportunity to score.
“We won’t look for excuses - the result is what it is. We have to manage the conditions better, and we didn’t do enough today.”