The Swedish striker limped off during the second half of his side's 3-1 win in the first leg of their UEFA Champions League quarter-final tie on Wednesday, and is now a major doubt for next week's return meeting at Stamford Bridge.
It was a largely quiet night at the Parc des Princes for Ibrahimovic, who was withdrawn after 68 minutes to be replaced by Lucas Moura.
"Zlatan felt a slight muscular pain - I'm not sure whether it's his calf or his hamstring," said Blanc. "We'll have to look after that but it will require a certain amount of rest."
Ezequiel Lavezzi put the hosts ahead in the opening four minutes, before Eden Hazard pulled Chelsea level from the penalty spot.
However, a David Luiz own goal and a stoppage-time strike from Javier Pastore gave PSG a comfortable cushion as they prepare to head to London.
But despite the impressive victory, Blanc insisted that his side could have done even better.
"You can always do better, but I think the boys gave everything," he added. "We've been a bit cautious in the building of our game. We were probably a bit afraid of Chelsea's counter-attacks.
"They are a very powerful team. We made them run, though, and scored that last-gasp goal.
"I think we managed to be better in the second half. We won more balls and Javier's goal was fantastic."
