Real's star forward, the prolific former Manchester United favourite, is poised to return to action for Wednesday's Champions League semi-final second leg against City at the Bernabeu.
Ronaldo missed last week's goalless first meeting at the Etihad Stadium with a thigh problem but is now ready to return after coming through training unscathed.
Pellegrini said: "Cristiano will always be a different player
He scores a lot of goals and has throughout his six years here.
"However, I don't think Real are just Cristiano Ronaldo
We must work as a team defending and attacking
It is not just against Ronaldo but against Real Madrid."
City have their own crack frontman in Sergio Aguero, who has scored 28 goals this season, and Pellegrini hopes the Argentinian will be back at his best after being rested for the weekend loss at Southampton.
Pellegrini said: "I always say these kind of games are decided by the best technical players
We have Sergio and I am sure we will see him in a good performance."
Pellegrini also intends to continue playing in the same free-spirited way that has seen them claim good results away at Borussia Monchengladbach, Sevilla, Dynamo Kiev and Paris St Germain this season.
He said: "In the three seasons in the Champions League we have played very well away.
"We will continue trying to play in exactly the same way
The pressure in the Bernabeu is high pressure but I think we have the personality and the football to try to beat them.
"Everyone must trust in their team
We trust in ours and I hope we can demonstrate it in the 90 minutes.
"We are sure we will need to make a very good performance to reach the final - it would be the first time we've reached it."
The match marks a return to the Bernabeu for Pellegrini, having spent a single season in charge of Real before being sacked in 2010 after finishing runners-up to Barcelona.
Again, he played down any suggestion of holding a grudge.
The Chilean said: "It is a stadium with good memories but I have been back many times
There is no problem
It was an important year here and I had the support of everyone."
Pellegrini confirmed Yaya Toure is fit and in contention to play after missing the last two games with a thigh injury.
Some confusion did arise as it was reported the midfielder had not travelled despite participating in an open training session this morning, but that was not true.
Pellegrini said: "I don't know the news that Toure wasn't travelling because he trained without problem the whole week.
"He has a lot of experience and quality
He won a Champions League for Barcelona here so he will be important."
One player who will not be involved, however, is full-back Pablo Zabaleta due to a muscle injury.
Pellegrini was speaking at a press conference on the eve of the match at the Bernabeu, where he was accompanied by defender Gael Clichy.
Clichy hopes City can make history and seize the chance to reach the final for the first time.
The France international said: "It's not every day you can play a semi-final of the Champions League but it will only be special if we go through.
"We're going to try really hard
It's going to be a really tough game, we want to make history and to go through."
Source : PA