The France international suffered a hamstring injury in January and was ruled out for up to a month by club medics.
Dembele's setback came less than two weeks after he returned to action after a more serious hamstring tear, which saw him sidelined for nearly four months.
The 20-year-old will not play a part in Barca's Copa del Rey semi-final second leg against Valencia on Friday (AEDT) but could be in line for the LaLiga game against Eibar on 18 February, which takes place just three days before the first leg of its UEFA Champions League last-16 tie with Chelsea.
"He's okay," Valverde said. "He's started training sessions. I hope he can come back into the squad for next week."
Gerard Pique is another who is likely to miss Friday's game at Mestalla, after he picked up a knock during the 1-1 derby draw with Espanyol.
Valverde refused to rule the centre-back out of the match but suggested January signing Yerry Mina could make his debut if Pique is unavailable.
"He finished the game in discomfort, with a little injury, but as of now he's not ruled out," said Valverde. "We'll see how he is today [Wednesday]. He's going to train and we'll see.
"Yerry is in the squad and ready to play. It depends on the coach's thinking whether he will start.
"The fact there are players who can play in different positions is an advantage for him and for the team. We have to decide depending on the situation.
"I knew Yerry Mina from watching videos and now from him training with us, but I don't know him in our competition. I hope he adapts well."
Barca beat Valencia 1-0 in the first leg at Camp Nou.