"(The result) is not a concern because we have a lot of missing players. "You cannot be worried in this moment about the scores, winning or losing."
The defensive trio should all be fine for the start of the season, with Kompany returning to Europe early for the birth of his child, Mangala taken ill and Demichelis still recovering from the Copa America.
But Fabian Delph is an unlikely starter for the early stages of the season, after the new signing was carried off with a hamstring injury against Real.
"Unfortunately Fabian has a problem with his hamstring," Pellegrini said. "This injury is not the best news. He was just starting the season with our team, but tomorrow we will have a more clear diagnosis from the doctor."
Friday night's match in front of a record crowd 99,384 ends City's fortnight in Australia. Pellegrini said he was delighted with the welcome in the city of their sister club, Melbourne City.
"It's a beautiful country with a lot of facilities, good weather, good training grounds," he said.
"I think we chose the correct way, the correct path to make the pre-season."
City claimed a penalty shoot-out win after a 2-2 draw with Roma on Tuesday night before their loss to Real.
Pellegrini's side now head to Vietnam and Germany for friendly matches before beginning the English Premier League season on August 10 against West Bromwich Albion.