The Chilean, who led debutants Malaga to the quarter-finals earlier this year, is in his first campaign at the Etihad Stadium and wants to improve on last season's performance by City who failed to reach the knockout stages.
"It would be a big mistake to think that playing a team with less history in Europe would be easier to play," Pellegrini told the club's website (www.mcfc.co.uk) on the eve of the Group D fixture against the Czech league winners in Plzen.
"Last season when the draw took place AC Milan and Zenit St Petersburg were happy to be drawn against Malaga and they felt they'd already qualified for the next round."
Pellegrini, who also led Villarreal to the semi-finals in 2006, was given some words of advice by former Manchester City manager Mark Hughes at the weekend.
Hughes, now in charge of Stoke City, said if his old club failed to progress in Europe it would be a "stick that people can use to hit them over the head with".
The other teams in Manchester City's group are holders Bayern Munich and CSKA Moscow.
"This is my fifth year in the Champions League and I am very happy about my last campaigns," said Pellegrini.
"It is not easy to reach the semi-finals with a team like Villarreal, or to make it to a quarter-final."