Bilbao revealed on Friday they had rejected a bid from United for highly-rated playmaker Herrera, with the English champions expected to come back with a new offer before the transfer window slams shut on Monday.
Despite the move speculation, Valverde has included Herrera in his squad to face Real Madrid on Sunday and says the midfielder has not intimated anything about his future plans.
"There has been quite a stir surrounding Ander," said Valverde. "He is fine to play. Whether he plays or not is another question. I have no doubts.
"Whether he plays is the decision of the manager - it is not only if a player feels ready. We have Mikel also, who is important for us.
"To play in his situation is not normal. I've spoken to him and he's within the right state of mind to play."
Meanwhile, Herrera's father, Pedro, claims it will be a difficult choice for the 24-year-old to leave Bilbao for United.
Speaking to Mundo Deportivo, Pedro said: "Ander is getting on very well at Athletic, very content.
"He's fought hard to come to this club and it's very difficult for him to leave.
"I think it's Manchester United's decision, since they have not found a replacement for Cesc Fabregas. They've decided to opt for a creative player and have thought about Ander."