The European champions beat Argentina's Estudiantes 2-1 after extra time to lift their sixth trophy this year, adding the world crown to La Liga, Champions League, King's Cup and Spanish and European Super Cups.
"Now we're going to descend a bit from our stardom, but we have talent and we got here with hard work. We're going to be alright," he told the post-final news conference on Saturday.
"Six titles is unequalled, this brings more responsibility ... We have to continue working to remain among the elite."
"I'll never forget it's the players who achieved this and the ones who gain me my prestige (as a coach)," added Guardiola, who had lost a world club final once before with Barcelona, as a player in 1992 in the former Intercontinental Cup.
Guardiola's big off-season signing Zlatan Ibrahimovic said: "Playing always to win, you have more chances of winning.
"One of the reasons I came to Barca was to win titles ... I hope we continue to win many more trophies."
Estudiantes coach Alejandro Sabella, whose team were looking for their second world title, praisedBarcelona's "tactical variety" and "calmness."
He also pointed to their strength in depth, adding that not even injuries could throw them off their game as they had international players on the bench.
Barcelona were hit by another injury during the match, with midfielder Seydou Keita injuring his thigh. He would be out for about three weeks, the club said.
Sabella said Estudiantes would regroup and focus on new goals, the Argentine Clausura championship starting at the end of next month and defending their Libertadores Cup title.
Brazilian Sergio Farias, coach of Asian champions Pohang Steelers of South Korea, who finished third in the seven-team tournament, said: "To get third place is a huge stimulus to the players.
"Having reached the standard we did to obtain third place, maybe we can improve."
Pohang beat Atlante of Mexico on penalties after a 1-1 draw.
