Real are still smarting from their unprecedented 4-0 drubbing on Tuesday by third-tier side Alcorcon in their King's Cup first leg, and doubts have been raised in the Spanish media about Pellegrini's future ahead of their la Liga match at home to city rivals Getafe on Saturday.
"I would like to send a message to calm the fans," Perez, who spent 250 million euros on players including Cristiano Ronaldo and Kaka in the close season, said on Wednesday.
"We have to remember that a lot of new players arrived before the start of the season and this requires a period of adaptation."
"The season is only two months old and we are still trying to create a team."
Tiny Alcorcon, who play in the same league as Real's youth team and have a budget more than 400 times smaller than the Spanish giants, managed to humiliate Pellegrini's side despite the presence of Spain defenders Raul Albiol and Alvaro Arbeloa, and several other internationals.
The defeat followed last week's 0-0 La Liga draw at Sporting Gijon that allowed champions Barcelona to open a three-point lead at the top of the standings and a 3-2 home loss to AC Milan in the Champions League.
TO THE DEATH
Albiol, who spent a season at Getafe in 2004-05, said he had not slept a wink on Tuesday night after the Alcorcon match.
"We are sad and upset but we know we have another match on Saturday and we have to turn the page," he said on the club's website.
"We are with the coach to the death and we have to translate his ideas onto the pitch."
Ronaldo will again be missing on Saturday and will be out of action at least until he has another test on his damaged ankle in a week's time, the club said on Wednesday.
They had won every game with their record signing in the side but have slumped to three defeats, a draw and only one victory in all competitions since his injury last month.
Getafe coach Michel, a former Real player and ex-director of their youth programme, said his players were full of confidence after Wednesday's 2-0 King's Cup win at home to Espanyol.
"We are coming to Madrid in good spirits and in good shape," Michel said after the match.
"Sometimes at the Bernabeu that's not enough but the important thing for us is that we play our game and stay solid."
Barcelona also won 2-0 in the Cup on Wednesday, with coach Pep Guardiola deploying a second-string side at third-tier Cultural Leonesa, and the European champions play at mid-table Osasuna on Saturday.
Also on Saturday, Quique Sanchez Flores makes his league debut as Atletico Madrid coach at Athletic Bilbao as he begins the task of turning around their troubled season, while third-placed Sevilla travel to promoted Xerez.
Undefeated Barca have 22 points from eight matches, Real have 19 and Sevilla 16. Valencia and Deportivo Coruna are both on 15 points in fourth and fifth respectively and surpris
