The Dutch striker has recently been linked with a move to White Hart Lane.
Athletic Bilbao's Carlos Gurpegi in action against AZ Alkmaar's Vincent Janssen
Kieft – who was capped 42 times by Holland and managed 194 goals in 402 club appearances – believes the AZ Alkmaar striker should take on the challenge at Tottenham for the good of his development.
“If Janssen has to choose between Ajax and Tottenham, he must go to London,” said Kieft.
“Yes there is Harry Kane. What could be better to try without any pressure as number 12 or 13 to make the great Kane nervous?
Tottenham's Harry Kane applauds fans after the game
“Regardless of the adventure and the financial gains, Janssen can only get better by training with better players every day.”
Spurs held discussions with the 21-year old in London last week, according to Sky Sports, and a deal looks like being a strong possibility.
His capture would provide much needed support for Harry Kane and would allow Mauricio Pochettino the ability to rotate far more effectively than he could last season.
Holland’s failure to qualify for Euro 2016 should make completing a deal slightly easier and Pochettino will hope to have his man in before the start of pre-season.
Next season will see a return to the Champions League for Spurs and their squad is in need of reinforcement if they are to compete both domestically and in Europe.
Quality cover is needed in central midfield and further attacking signings may well be pursued even if a deal for Janssen is completed.