Hart played on after suffering a cut close to the eye to make a number of crucial saves as City claimed top spot in the Barclays Premier League with a hard-fought 1-0 win at the Etihad Stadium.
A club official later confirmed Hart had needed five stitches after being hurt in a collision with Palace striker Cameron Jerome during the first half.
His man-of-the-match performance in the second half, as Palace grew in confidence, made light of the injury and fully justified his recent recall to the side after being dropped for a spell.
Pellegrini, who had been unaware stitches were needed as he gave his post-match press conference, said: "It was not a serious problem. The doctors said he doesn't have serious problem. There isn't a problem with his sight."
Hart was dropped by Pellegrini at the end of October after a series of high-profile errors for club and country.
Costel Pantilimon took his place for seven Premier League games and Pellegrini believes the break has done Hart good.
He said: "I repeat what I said last week, it was very good for Joe Hart to have a rest.
"He needed a rest and he is playing at his normal performance level, as the good goalkeeper he is.
"He worked very hard but he was always confident he would return to his position."
Pellegrini made six changes for the fixture, which came just two days after the Boxing Day win over Liverpool, and the intensity level appeared to drop.
It took until the 66th minute for Edin Dzeko to break the deadlock against a resilient Palace side who might feel unfortunate not to have claimed a point.
But Pellegrini claimed the approach of Palace had blunted his side's normally free-flowing attack.
He said: "I don't think we were fortunate to win the game today.
"Just one team wanted to play the 90 minutes and the other wanted to stay in their own goal.
"I was absolutely sure before it would be a very difficult game.
"It is impossible to play 44 hours after the tough game we played against Liverpool and I knew our team was not fresh so it would be a very difficult game.
"That's why it is so important to know how to win 1-0."