The France international joined Barca from Atletico Madrid for €120million in July but has failed to find his best form in Catalonia.
He has been used predominantly in a wide role and has scored just four goals in 14 matches in all competitions, firing blanks in his last four outings.
Having spent five seasons playing a different type of football under Diego Simeone at Atletico, Griezmann has been told by Valverde to adapt his style of play.
🔊 Ernesto Valverde: “Celta have good players and it’s not normal for them to have so few goals with the players they have. It’s a team that will get out of the bottom part of the standings. They have talent and they’ll show it. #BarçaCelta pic.twitter.com/RWJGS10043— FC Barcelona (@FCBarcelona) November 8, 2019
"A lot is said about his situation, but I think it's a lot simpler than it seems," he said at Friday's news conference. "He is used to a different type of football.
"I played against Simeone teams lots - his players drop back quickly. As soon as they lose the ball, they run back.
"Players like Koke and Saul [Niguez], [Diego] Costa and [Alvaro] Morata. That's the way Atletico play, a side that likes to get back and fill space. At Barcelona, we play a short passing game.
"It's a case of looking for players and seeing space. Antoine is generous in that way - in fact we ask that of him, to lose his marker and create space.
"When you go forward you must come back but I think he needs to mature into the way we play. Likewise, our players need to get used to the things Antoine does.
"It's not been easy in his first year, but once players start to gel it rolls a lot more smoothly."
Griezmann has played a full part in Barcelona's last two matches, the LaLiga champions following up a 3-1 league loss to Levante with a goalless home draw against Slavia Prague in the Champions League.
The 28-year-old was not alone in being criticised for his display against Slavia, with Ousmane Dembele also failing to impress prior to being replaced by teenage forward Ansu Fati.
"Tuesday's game was difficult. Ousmane could have done more in the first half but did better after half-time. I still see Ansu as a better option off the bench given his age," Valverde added.
Jordi Alba suffered a relapse of a previous hamstring injury against Slavia, potentially opening the door for Junior Firpo to start for the first time since September when Celta Vigo travel to Camp Nou on Saturday.
"This could be a game for him to have a chance," Valverde said. "We are happy with him. He is a good player and will do good things for us."