"We have had a meeting with the family and on Monday we will have a meeting with Ansu and the club doctors to make a decision," Xavi said in Saturday's news conference.
"It's a recurring injury. It's out of our control. We will now get an exhaustive and specific plan in place to ensure that he never gets injured again."
Ansu, 19, had only returned to action on Jan. 12 after being sidelined since November with a hamstring injury.
"It's a pity," Xavi said. "He had just recovered his confidence and was doing well. He is very affected.
"We need him, we have lost an impressive footballer, so it affects us all but most of all, Ansu.
"We have to recover him mentally and make him forget about the injuries.
"We have to be positive and hope that he doesn't get injured anymore."
Xavi did not reveal whether Ousmane Dembele will be included in the squad for Sunday's league game at Alaves but did say the player's situation "has not changed." The forward was not selected for the midweek game at Athletic.
Dembele has not signed a new contract at the Camp Nou with just six months to run on his deal and has turned down all offers of an extension.
"There's no debate," Xavi said. "I've been very clear. It depends on him.
"Ousmane's situation hasn't changed. He knows perfectly well what his situation is.
"He is calm, he is training well and he is part of our training group. There are still days left [in the transfer window] but there's no alternative [he either signs or leaves]."
With Dembele's future up in the air and Ansu facing a lengthy spell out, Xavi has requested that Barca bring in reinforcements before the transfer window closes in 10 days.
"We are working on getting some signings," Xavi said. "I've been very clear with [Barca's football director Mateu] Alemany and with the club president [Joan Laporta] as to what areas we need to reinforce. But from what we want to what we can get, there's a stretch. We will see what can be done considering the wage bill. There are still days left."
Barca, who are also without injured striker Memphis Depay for the game at Alaves, are hoping to leave behind a disappointing week.
"If you work well during the week but you don't get results, it's a worry," Xavi said. "My biggest concern is not getting results. I know we must be the first to be patient. We have to persevere. If I weren't optimistic, I would go home.
"We are at the beginning of something important and we must have faith. We need a win urgently to climb to the Champions League qualifying zone, which is our first aim of the season."