The Brazilian forward sat out of the Reds' opening game of the season, a 3-3 draw at Watford, having handed in a transfer request ahead of the opening weekend of the Premier League weekend.
Klopp, who has been open about his disappointment with Coutinho pushing to leave Liverpool, refused to be drawn on the 25-year-old's attitude as he continues his attempts to force an exit.
"Phil is not available. He’s not in training so far," the Anfield coach told reporters on Thursday. "I think it is still the back injury, nobody has told me anything different.
"I’m not sure that I even have to answer [whether there have been Barca negotations] because the club has already said what we have to say.
"There’s no news from me because nobody told me any different since we spoke last time about this.
"I have nothing to say about his attitude because, since he got the back injury, he hasn’t been in training.
"When I asked the medical department how he’s doing, they had no complaints so that’s how it is. I’ve got nothing bad to say about his attitude."
Barcelona are expected to return with a bid in excess of £120 million for Coutinho, making him the second-most expensive player of all-time behind Neymar should Liverpool accept.
However, the club have maintained that their star player is not for sale at any price and claim they will reject any further Barca advances .
Barcelona were also criticised for claiming that a deal for Ousmane Dembele is close earlier on Thursday by Borussia Dortmund, who insist the opposite is true.
"I have no reaction, actually," Klopp replied when asked about Barcelona general manager Pep Segura's suggestion that a Coutinho deal is imminent. "I saw the game but forgot to watch the interviews afterwards.
"There’s nothing to say from my side - I don’t know why other people are saying what they’re saying."
Barcelona are desperate for attacking reinforcements - and are not short of money to spend - having lost Neymar to Paris Saint-Germain earlier this month for €222m when they bid his release clause.