City overcame record 13-time Champions League winners Real 4-2 on aggregate to progress to the quarter-finals.
Guardiola, though, said there was no time to sit back and revel in the win.
"We're here to try and win the Champions League," said the two-time winner when in charge of Barcelona.
"If we think that [beating Real] is enough we will show how small we are. If you want to win you have to beat the big clubs.
"I just spoke with the scouting department about Lyon and they told me to be alert. The players will go to Portugal to try to make the next step.
"We more than deserve to be in the next stage.