The Chilean was left furious following a below-par display against a Foxes side who posed the greater threat throughout.
Most disappointing of all for the 62-year old, was the fact that City conceded from two set pieces but he did pay tribute to Leicester and admitted that the visitors were good value for their win.
Pellegrini told journalists: “I don’t think it’s fair to make excuses.
“A lot of things went wrong. We played against a very good team.
“It’s fair to give them the merit they have, they’re playing well in a good moment. After that, we defended very bad. Especially to concede two goals from set pieces.
“On top of that, with a lot of possession, we didn’t create enough.
“I think we didn’t defend well because they had other chances. I don’t complain about one action of the game. I just complain about the way we played today.
“We had a chance to recover points at home, now we’re six points behind Leicester. Now we have 39 points more to play for. We must focus game by game and try to beat Spurs here. We will also see what happens between Arsenal and Leicester. So many things can happen.
“Of course though, this was a defeat we didn’t expect.”
City were hit with yet another injury blow in the game as David Silva limped off with a recurrence of his ankle injury.
The Spanish playmaker now faces a race to be fit for Sunday’s game against Spurs, according to the boss.
If Silva does miss out, City could be left with just 13 fit senior players for Tottenham as the injury count continues to rise.
“He had a twist in the same ankle,” Pellegrini said.
“I think it will be difficult for him to recover soon. We will see before the weekend.
“In football, things change from one week to another. We’re not in our best moment - we have just 14 players fit and we’re playing a lot of games. We need to recover as soon as we can from this defeat.”
The result left many pundits wondering whether Leicester City can now be considered favourites for the Premier League title.
Manuel had his say on the matter, adding: “If Leicester continue playing the way they are of course [they are favourites]. There are 13 games more so it’s difficult to make a prediction on the future.”
