Gallas will not kick a ball on the opening day of the Premier League season as he is out of contract after allowing his contract with Arsenal to run down.
Redknapp has spoken to Gallas' representatives about a move and has played down concerns Spurs fans may have about signing a former Arsenal player.
"I like Gallas," Redknapp said. "I think he's a great free transfer. It is a possibility. His people have rung up and we spoke about it.
"He is an experienced player. He has played at the top level, he won championships with Chelsea.
"You can go on for ever about the fact he played for Arsenal. He played for Chelsea as well. We put too much importance on that all the time. If he comes in and plays rubbish then the crowd will slaughter him. If he comes in and plays great they will love him. That is football."