Haaland penned a 10-year contract on Friday and Guardiola concedes the Norway international will always be his first-choice in attack.
City are closing a deal for Eintracht Frankfurt striker Omar Marmoush today.
Guardiola said: "The bigger strikers will not come to be a replacement for Erling, so we have to find them young to accept the role.
"Or they're different players - like Oscar (Bobb), (James) McAtee, Phil (Foden), and maybe without Erling we'll play a different way, with a false nine, with alternatives, with more runners from outside, more runners for the channels inside. We will find solutions.
"We could not go to sign (Kylian) Mbappe, for example, as a top-class player because normally we play with just one striker.
"But of course we have alternatives just in case Erling cannot play all the minutes. We have other options."