The visitors found it tough going at the Westfalenstadion, creating very few chances to score and needing Marc-Andre ter Stegen to save a penalty from Marco Reus.
Valverde said it was a tough game for the Spanish giants and offered his thoughts after the match.
“The result is what is it. We suffered a lot and you have to admit that. They arrived with more danger and we were missing some depth in the last few metres.
“They had the penalty, they hit the post. They are very strong at home, this is the start and it was a tough match for us.
“There were some moments when we lost the ball in important zones and they got three or four counters and it complicated things for us but Marc was really good. And while we dominated the end of the game, we hardly had any chances.”
The other match in Group F also saw a draw, as Inter Milan rescued a point against Slavia Prague thanks to a stoppage-time equaliser.
Barcelona’s next Champions League tie is against Inter at the Camp Nou on October 2.