Guardiola has the chance to exit the club with the 14th trophy of his four-year reign if Barca can beat Athletic Bilbao at the Calderon in Madrid on Friday.
The build up to his departure has been dominated by media rumours that he was unhappy with the way club handled the news that his friend and assistant Vilanova was to succeed him, with suggestions that he did not know.
This has led to sniping between the former president Joan Laporta and incumbent Sandro Rosell that has threatened to de-stabilise the club.
"After being knocked out by Chelsea I rang Tito and I told him the moment had arrived and that they were going to offer him the position, and that he should do what he thought best," Guardiola said referring to their Champions League semi-final exit.
"Who am I to deny him something? I told him 'whatever decision you take I will support you.' I have known him since I was 13."
As to the exchanges between Laporta, who appointed him as coach in 2008, and Rosell, Guardiola said: "I have a marvellous relationship with Laporta and Rosell, and I am grateful to them both for the way they have left me to get on with my job.
"I have told them both I am going, taking a step to the side, and I have asked them not to use my name."
Guardiola was also pressed about comments made by the president of the Madrid regional government, who has stirred up a political storm by saying that if fans whistled the national anthem on Friday, the game should be suspended.
At the Cup final between Barca and Bilbao in Valencia in 2009, when Guardiola lifted his first trophy as coach, Basque and Catalan nationalists among the fans whistled the Spanish national anthem.
"I am not in favour of the whistling of the national anthem," the former Spanish international said.
"But I think it is a poor show the president of the region won't be there. She would have honoured us with her presence, but I respect her decision not to attend.
"Tomorrow it is the Copa del Rey final which should be all about football. Other issues can be sorted out in Parliament."
Barca take on a Bilbao side who, after impressing during the season, have dropped away badly in the last few weeks of the campaign.
Guardiola was expecting a different side to the one beaten 3-0 by Atletico Madrid final in Bucharest earlier this month.
"I expect to see the side who beat Manchester United and Schalke 04," he said. "It is a side which never gives up. It will be an extremely tough final."
Earlier, Bilbao coach Marcelo Bielsa was asked how he was going to stop Barca forward Lionel Messi, who has netted an astonishing 72 goals in all competitions this season.
"Messi has solutions for most of the problems you present him with," Bielsa said of his fellow Argentine.
"We have to try and make sure he doesn't find those solutions and that the defenders don't even let him try."