"Right now I would rather take a bit more time and when I have decided I'll inform the club," the 41-year-old former Barca and Spain midfielder, who prefers to renew his deal on an annual basis, told a news conference.
"I know that I would not be better off somewhere else but I need to feel it," he added ahead of Barca's La Liga game at home to Valencia on Sunday.
"I cannot work at such a demanding club if I don't have strength. I don't have it clear in my mind, that's why I am not saying whether the cycle has ended or whether I will extend.
"If the club sets a deadline we'll talk and I'll decide. In the meantime, I'll focus on the day-to-day."
Barca President Sandro Rosell is desperate to persuade Guardiola, who has led the club to 13 trophies since taking over in 2008, to stay on, although he has refrained from putting too much public pressure on him.
Guardiola waited until February 8 last year before agreeing a new deal and went on to capture a third straight La Liga title and a second Champions League crown, as well as the Spanish and European Super Cups and the Club World Cup.
Pep praised Barca's World Player of the Year Lionel Messi, who is set to make his 200th league appearance for the club on Sunday, calling the Argentina forward the most competitive player he had seen.
The 24-year-old has netted 142 goals in 199 matches since making his La Liga debut as a 17-year-old against Espanyol in October 2004 and has 23 in 22 games this season, four behind Real forward and top scorer Cristiano Ronaldo.
