Van der Vaart was a graduate of the Dutch champions' revered youth academy and made over 100 first-team appearances for the club between 2002 and 2005, before joining Hamburg.
After spells at Real Madrid and Tottenham the attacking midfielder returned to the Bundesliga outfit in August 2012.
However, Hamburg endured a tough 2013-14 campaign and only avoided dropping into the second tier by winning a two-legged relegation play-off with Greuther Furth, and Van der Vaart has since been linked with a reunion with ex-Spurs manager Harry Redknapp at QPR.
De Boer also confirmed his interest in bringing the 31-year-old to the Amsterdam Arena, but Van der Vaart is focused on helping Hamburg improve in Germany's top tier.
"I had contact with Rafael two weeks ago to sound out if he was open to a return," Van der Vaart said at a news conference ahead of Ajax's Eredivisie opener with Vitesse.
"He has experience. He's just not ready for a return. He wants to put a very bad season behind him. He wants to focus on Hamburg and I can understand that."
Ajax are gunning for a record-breaking fifth straight title in the Dutch top flight and welcome Vitesse for their curtain-raiser on Sunday.
