Liverpool have signed Jeremy Jacquet and Victor Munoz, but lost Mohamed Salah, Andy Robertson and Ibrahima Konate, while Hugo Ekitike, Conor Bradley and Giovanni Leoni are sidelined through injury.
"I think it's difficult to say a number (of players needed) when the market is open, and you have to be always open to new options to improve the squad," the Spaniard told reporters in Chicago on Tuesday.
"There are obvious situations that we know where we need to sign players. A winger, for example - we definitely need to sign a winger.
"But there are other situations that we will have to analyse what the market gives you, what's the cost, how we also see the players we have. We have some tricky positions where we have injured players that we trust but is still not the ideal situation."
Salah, Konate and Robertson's departures have also left Liverpool with a dearth of experience in their squad.
Goalkeeper Alisson is another veteran whose future at Anfield is uncertain, but Iraola said he was keen to keep the Brazil international.
"I think he's someone that definitely will help us in this process of adaptation of the new signings, of the new players, the young players," he added.
"We need the references like Virgil (van Dijk), like Alisson, like Joe Gomez, players that have been here for a long time. And I'm sure we will have this help, yes."
Liverpool begin their pre-season preparations with a match against Sunderland in Nashville on Saturday, before taking on Wrexham, Leeds United, AS Monaco and Como.
They play their first game of the Premier League season away to Newcastle on August 23.