Defoe broke down during a session in Al Ahli's Rashid Stadium where Spurs were training as part of their five-day break between matches.
It is unclear how long the striker will be out of action for, but the club will hope that the injury is not a recurrence of the ankle ligament damage that ruled him out for eight weeks following England's 3-1 win over Switzerland in September.
Defoe is yet to score in the league this season but news of his injury is still a blow to Redknapp due to the fact that he is already without several key players through injury.
"Defoe has an injury again. He's had a problem with his ankle before and it didn't feel too good," Redknapp said in Dubai-based newspaper The National.
"We're trying to finish in the top four and it's so close. But we've got so many players injured, people forget.
"We've got Tom Huddlestone, Younes Kaboul, Ledley King, [Jonathan] Woodgate, [Gareth] Bale, [Rafael] Van der Vaart.
"If you could pick a team of injured players it would be a fantastic team."
Source: PA
Source: PA