The former Real Madrid man played an hour of Tottenham's 1-0 win against AC Milan last Tuesday after picking up the injury in the club's 2-1 win at Bolton on February 5.
Redknapp confirmed that his star forward suffered a recurrence of the problem in training on Sunday.
But Redknapp is confident that the Dutchman will be back to full fitness for Tottenham's game at Wolves on March 6 and the club's crucial Champions League clash with AC Milan three days later.
Redknapp said: "Rafa did his calf again in training so he's struggling (for Tuesday's game).
"He missed a couple of games, played in Milan, got through 70 minutes and then Sunday morning didn't feel good. It's a blow, he is a fantastic player. We need him but we can't get that run out of him. I'm hoping he will be back for Wolves. He should be okay, it's not a tear."
Source: PA
Source: PA