Ivory Coast international Toure has a heel problem that will prevent him playing at Carrow Road.
And Pellegrini says it is too early to know if Toure will recover in time to play against Dynamo at the Etihad Stadium, when City will attempt to protect a 3-1 lead in the Champions League last-16 tie.
"Yaya has a problem in his heel," the coach told reporters. "We will see next week if he can improve.
"We don't know [if Toure will be fit to face Kiev]. We must see, because it is a pain in his heel.
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"Sergio Aguero had the same problem one month ago, so we will see how Yaya is."
However, Pellegrini is set to welcome back influential attacking midfielder Kevin De Bruyne from a knee injury after the upcoming international break.
Samir Nasri is also close to returning from a hamstring injury that has sidelined him since October, while Fabian Delph (Achilles) is also nearing a comeback.
"Well it's very important [to have De Bruyne back]," Pellegrini added. "But also Fabian and Samir Nasri.
"Because the three of them play in a similar position so maybe we didn't have too many chances to make changes.
"I hope that after the international break they can work another 15 days more. The three of them will be fit for the rest of the season. That can be very important for us."