The Uruguayan came off the bench in Friday's clash - which saw Remy Cabella open the scoring for the hosts before PSG defender Maxwell equalised - but was unable to score the winner for the reigning French champions.
Despite this, Blanc was pleased with how his €63 million striking recruit played in his first game for PSG and hopes the game time following the summer break will help improve his fitness.
"He created depth," the Frenchman told reporters after the game. "He also had a great opportunity that was blocked by a defender. He will give us the depth we need.
"He is not 100 percent, far from it. But he is still an important player and, in particular, a goalscorer. This is a player who has had about 10 days of preparation. He needs to play.
"There will be no friendly matches for him to reach perfect condition so therefore it must be done in an official match."
He also added that the ex-Napoli forward needs time to adapt to playing alongside fellow former Serie A star Zlatan Ibrahimovic for les Parisiens.
"We will have to work and especially focus on them working together," Blanc said. "It is one of the first times they [Cavani and Ibrahimovic] have played minutes together.
"A balance must be found to enable them to be effective."PSG failed to take advantage of a red card to Montpellier's Abdelhamid El Kaoutari with fewer than 20 minutes to go and Blanc admits that victory for his side would not have been deserved.
"We hoped for a better result. You have to be logical, but we provided too little in the first half to my liking," the 47-year-old added. "We made too many technical errors that allowed Montpellier to open the scoring. The first half was very bad for us.
"The second half was better, as we finally used the wings. Late in the game we could have won, even though I think a draw is a fair result.
"We could have lost that game, but we knew not to lose. We are not content. This was the minimum we could do this evening."