"It's difficult for Harty," said Redknapp. "I took him there. It's just sad.
"As somebody said they've (Portsmouth) found the only Arab who seems to be struggling for money. Everybody else has got millions of it. It's sad to see them in that situation."
Redknapp, however, defended his own record at Fratton Park which saw a host of big name players win the FA Cup at Wembley less than 18 months ago.
Redknapp said: "People say 'You bought players like (Lassana) Diarra.' Yeah, well they (Portsmouth) paid £5m for Diarra and paid him £50,000 a week.
"But he was there for less than a year and they sold him for £22m. Where is that money? Where is the money for Glen Johnson? Where does it all go? It's sad to see."
Redknapp admitted he realised there were problems at Portsmouth under former owner Sasha Gaydamak but he urged Hart to keep believing that the club's problems could be surmounted.
"You've got to keep going," said Redknapp. "I sensed with the previous owner things were not right. You need owners who are interested in the football club, who want to support the team.
"I don't know why people get involved in football clubs when they are not really that interested in the club. That is what has happened to Portsmouth in my opinion.
"When they got £5m compensation for me they were really happy to accept the money. In fact, I think they called a taxi for me."