While Anfield boss Kenny Dalglish has strengthened in attacking positions with the likes of Charlie Adam, Jordan Henderson and Stewart Downing, it is believed that the Merseyside club are on the lookout for a centre-back.
Despite links with Birmingham City defender Scott Dann, Barnes is confident that Cahill would fit into the Liverpool squad.
“Cahill is a fantastic player and I’m surprised there have not been more noises made about him,” Barnes told talkSPORT.
“There are a lot of clubs looking for centre-backs and he’d be a fantastic signing for Liverpool. Another striker would be nice, but defensively is where we really need it [strengthening]. And Cahill would be perfect.”
Arsenal, who host Liverpool at the Emirates this Saturday, are also reportedly interested in the 25-year-old.