Former team-mates Van der Vaart and Heitinga both began their careers at Ajax and have played together at international level for Holland.
After Fulham's relegation from the Premier League, Heitinga has been released and is available on a free transfer, with Hertha Berlin said to be in talks with the centre-back and his representatives.
Speaking to Berlin-based newspaper BZ, former Tottenham midfielder Van der Vaart, who is now with Hamburg, claimed Heitinga would be a good signing for the Olympiastadion side.
"Should Johnny join Hertha Berlin, they would be signing a top-quality defender," said Van der Vaart.
"He has picked up a lot of valuable experience in the top leagues of European football.
"In addition, he is a true leader that deals exceptionally well with young players in a squad."