The Premier League challengers went ahead through Alvaro Negredo in first-half injury time, but Rovers captain Scott Dann netted an equaliser for the Championship side in the second half to force a replay at the Etihad.
The City boss confirmed there are currently no deals in place for the club, but is open to bringing new faces into his squad should any opportunities present themselves.
"For the moment we will stay exactly the same," he told BT Sport. "What I am saying doesn't mean that we cannot do maybe something from now till the end of January, but for the moment, nothing important."
Last year's beaten finalists were out of sorts for large parts of the game at Ewood Park but Pellegrini was relaxed after the game, stating that Gary Bowyer's men were more "motivated" for the visit of City.
"No, we were not lucky (to avoid defeat)," he told reporters. "I think it was a very close match and we had more options than Blackburn Rovers, more clear options, but we play against a very strong team here at home with lots of motivation.
"Disappointed? No. Of course everyone wants to win all the games but I repeat we played against a very strong team at home.
"I'm sure if Blackburn play the same way (in the Championship) they would maybe be in a different position in the table.
"It's normal (to have) motivation when they play against us."