The 18-year-old, who was born in Belgium, is eligible to compete for the Three Lions due to FIFA residency rules, while Albania and Croatia are also said to be possible options for the youngster.
While the likes of England cricketer Kevin Pietersen have waded into the debate, using non-England-born sportsmen such as Justin Rose and Mo Farah as examples, Redknapp believes that the football national team should remain English.
"I'm in Jack Wilshere's corner," Redknapp told BBC Radio Four. "There are several clubs in the Premier League now whose youth teams are absolutely full up with players who are bought in from other clubs abroad, and we'll end up with no English kids in the team.
"I'm absolutely with Jack. The English kids who go to academies at nine, eight, 10 years of age and striving to be professionals, there will be no future for them in the England team, I don't think, if we allow this to happen."
England are preparing to take on Montenegro in their penultimate World Cup qualifier on Friday.