The 25-year-old is close to joining Spurs in a £2.5million move.
It was Redknapp who signed Kranjcar for Portsmouth, during his time as manager at the club.
Redknapp told The Sun: “I’m really delighted. I signed him for Portsmouth and he’s a fantastic player and a great lad.
“I’ve already got two fantastic Croatian players – Modric and Vedran Corluka – who can help him settle in.”