Messi made his first appearance of the season after recovering from a calf injury in Barca's goalless draw away to Dortmund in their Group F opener on Tuesday.
The Barca captain had been sidelined up until his second-half introduction against Dortmund, though Messi was a peripheral figure for the visitors.
Leo Messi is back for Barça after 115 days pic.twitter.com/WPfZBb43Rk— FC Barcelona (@FCBarcelona) September 17, 2019
"He's like any player who hasn't had a pre-season," Valverde said.
"He's had to play in a game at an incredible pace, which had already started, all without preparation.
"It's his first 30 minutes. He's done enough. It was also the first full game for Luis Suarez."
ICYMI: Match report 👇 https://t.co/7xt1456Dhz— FC Barcelona (@FCBarcelona) September 18, 2019
Barca had goalkeeper Marc-Andre ter Stegen to thank for securing a point after the German star saved Marco Reus' second-half penalty.
Ter Stegen thwarted Dortmund on more than one occasion in the second 45 minutes and Valverde hailed the Germany international.
"In LaLiga [Santander] we were saying that opponents score against us," Valverde added. "But tonight, he was very good. We have a great goalkeeper and we benefit from that."
On denying Reus from the penalty spot, Ter Stegen said: It's hard to study, Reus always changes. It was a feeling I had [going to his left] and I'm glad that I could save it."