Premier league champions City have already won the Carabao Cup and can return to the top of the table with a win at home to Cardiff on Wednesday.
They then face Brighton in the FA Cup semi-finals on Saturday and Tottenham in the first leg of their Champions League quarter-final on 9 April.
“In one week or three days we can lose all three titles,” Guardiola said.
The former Barcelona coach has won two League Cups and last season’s Premier League since joining City in the summer of 2016.
He continues to play down the chances of winning all four trophies this season: “I said many times, ask me at the end of April.
“Why talk about the quadruple when in this country – a legendary country – it has never happened before.
“Legendary teams like Liverpool, the period [of Manchester United] with Sir Alex Ferguson, Jose Mourinho at Chelsea, Arsene Wenger with Arsenal – no one did it. So why should we do it?
“I’m not in the minds of my players and the fans to tell them what to think.
“If they want to dream and think about winning everything, I’m not a guy to say anything.
“Of course we are there but I said to the players, ‘Forget about it, don’t think too much. In one week or three days we can lose all three titles, that’s the reality’.
“‘I know in your heads we can win all the titles, but for now it’s Cardiff.”
City defended their cup title with victory on penalties against Chelsea in February but Liverpool are two points ahead of them in the Premier League, although Jurgen Klopp’s team have played a game more.
Guardiola claimed he was not surprised by the Reds’ last-gasp win over Tottenham on Sunday, Liverpool’s third success of the season as a result of a goal in the 9
