"I made a big mistake, which was to start off by winning four titles," Benitez, who took over at Anfield in the summer of 2004, told a forum in his native Madrid on Wednesday.
"Then people ask more of you, when in reality in the Premier League it's taken for granted that a manager needs time at the start to adapt."
Benitez, who has been linked with jobs in Italy, said he intended to see out his contract, which runs until 2014, and was determined to build a competitive team.
"My future is Liverpool and I have had no offers (from other clubs)," he said.
In his first season in charge, Benitez led Liverpool to a Champions League triumph and European Super Cup in 2005 followed by the FA Cup and Charity Shield in 2006.
A title drought has followed and Liverpool finished seventh in the league last season, 23 points behind champions Chelsea.
Senior Liverpool players, including Spain striker Fernando Torres and captain Steven Gerrard, have urged the club to make some high profile signings before next season.
But American owners Tom Hicks and George Gillett put the club up for sale last month and British media have reported the club's debts are more than 350 million pounds ($499 million).
"I have had a couple of meetings with the new (chairman Martin Broughton) to clarify the situation," Benitez said.
"We need to know how much money we have, and that also depends on (player) sales."
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