City have confirmed they are appealing the sanction handed down by UEFA after being found guilty of breaching the Financial Fair Play (FFP) regulations.
And in a press conference on Tuesday, Barcelona president Josep Maria Bartomeu appeared to have a subtle dig at the Premier League champions.
"I would like to thank UEFA regarding FFP, they've been doing fantastic work in the last couple of years," Bartomeu said, as per AFP.
"We have regular investigations and we have supported UEFA in everything it does in football."
Guardiola was then asked about the comments of his former club's president after their victory over West Ham United on Wednesday evening and the Spaniard barely minced his words.
"If they are happy we are suspended, I say to the president of Barcelona, let us appeal," Guardiola said, as quoted by ESPN FC.
"The people [at City] right now trust what they have done so that is what we are going to do. We're going to appeal and maybe it happens, but don't talk too loud, Barcelona.
"That is my advice because everybody is involved sometimes in situations. We are going to appeal and hopefully, in the future, we can play in the Champions League against Barcelona."