Barcola was forced off after an hour of Liverpool's Champions League win over Atletico Madrid, and the France international is still without a goal in three appearances since his big-money move from Paris Saint-Germain.
Speaking on the eve of Liverpool's Carabao Cup third-round tie against Tottenham, Iraola confirmed his summer signing was not yet ready to return to full training with the group.
"He is not ready to train with the team yet," Iraola said. "He is training on his own, but he has started touching the ball. We want him back as soon as possible. He still has some way to go and it will take time."
The Liverpool boss suggested defender Giovanni Leoni, who has been out with a long-term knee injury since last September, may now be closer to a return than Barcola.
"With all these long-term injuries, I think Leoni has a slight edge on him," Iraola said.
Barcola arrived at Anfield in one of the marquee deals of the summer transfer window, in a deal worth up to £123 million, and made his first start for the club in the Atletico Madrid match before being substituted with what was later described as cramp rather than a serious injury at the time.
The 24-year-old had previously come off the bench for his Liverpool debut in a 2-0 win at Ipswich Town, but has yet to open his account in a red shirt since his summer arrival from the French champions.
Liverpool host Tottenham in the League Cup on Tuesday, with Iraola's side looking to build on their recent form as they continue to manage a lengthy list of players working their way back from injury, including Federico Chiesa and Conor Bradley, both of whom are also nearing their own returns to full fitness.