In 2013, City's online scouting network had been hacked by a rival Premier League club who accessed their database of player targets.
The Scout 7 system was password protected – but City believe their network was illegally accessed.
It's emerged in The Times that Liverpool are believed to have made City a £1million payment in a confidential settlement of the data breach.
Guardiola said: “Today there are not secrets any more. Look what happened in the big governments in the states and Russia and everywhere everyone knows it.
“No secrets anymore. You want to keep a secret? Don't tell to a friend, on devices or mobile phone, today anything can happen."