The Argentine is set to spend the next three months on the sidelines while he undergoes “a diagnostic and therapeutic process” following a cardiological evaluation.
The former City striker was admitted to hospital on Saturday after being withdrawn early in Barcelona’s 1-1 draw against Alaves in La Liga.
Aguero spent 10 years at City and is the Club’s all-time leading goalscorer having scored a remarkable 260 goals in 390 matches before moving to the Camp Nou in the summer.
Guardiola has spoken to Aguero via his agent and says ensuring he makes a full recovery is the priority.
“It was difficult news for everyone, especially him and his family,” Guardiola said.
“We wish him well - he knows it. From our chairman and all our players and staff, we wish him a safe recovery.
“Life is much more important than anything else, and he knows that.
“He is in good hands who will take care of him. We wish him a speedy recovery.
“If it’s possible to play again then okay, if not he must enjoy his life.”
Meanwhile, Walker says he is pleased Aguero was able to walk off the pitch and is in a stable condition.
“It’s a shock when it happens to anyone,” he said. “I played with Christian [Eriksen, who suffered a cardiac arrest while playing for Denmark against Finland at Euro 2020]. You think about them and the family.
“I am glad Aguero is okay. We are athletes, we train really hard every day, but with these things you have to take certain precautions. His health is more important than anything.
“We are all human in more ways than one. We make mistakes as every human does.
“Health is key. As long as Serg is okay.
“I know Christian is fine, I spoke to him two weeks ago. Hopefully we don’t see more of this.”
