Speaking on a visit to Paris for the launch of the French edition of her book 'Mighty Be Our Powers', Ms Gboweee said: "People are very disappointed. We have a deficit when it comes to having a moral voice in the country."
Ms Gbowee, who said she felt guilty for not speaking out earlier, also revealed that she was stepping down as the head of Liberia's reconciliation commission in frustration at its lack of progress.
"We worked hard for peace," she said, adding that Ms Sirleaf herself was critical of the regime of William Richard Tolbert, who was Liberia's president from 1971 to 1980.
Mr Tolbert like Ms Sirleaf belonged to Liberia's elite Congo Liberian social class whose members descended from freed American slaves dominated the country's political landscape. They are accused of ignoring the masses.
Mr Tolbert had placed cronies and family members in top jobs before being toppled in a violent coup.
"What has changed?" said Ms Gbowee. "Her sons are on the board of oil companies and one is the deputy governor of the central bank. The gap between the rich and poor is growing. You are either rich or dirt poor, there's no middle class."
The feisty Ms Gbowee, who says her mission in life is to fight injustice and bring peace, said she was resigning as head of the National Peace and Reconciliation Initiative as "not enough is being done for national healing."
She added: "I feel I have been a disappointment to myself and Liberia. Not speaking is as bad as being part of the system. Some may say I am a coward but the opportunity to speak out has come here.
"I will also speak about it when I get home."
Ms Gbowee, Ms Sirleaf and Tawakkul Karman, a Yemeni journalist and a leading figure in anti-government protests, were jointly awarded the Nobel Peace Prize in 2011 for "for their non-violent struggle for the safety of women and for women's rights to full participation in peace-building work".
Liberia reeled under two back-to-back civil conflicts that lasted 14 years. Marked by extreme brutality they claimed the lives of 250,000 people.
When first elected, Ms Sirleaf declared war on corruption, but failed to make serious inroads despite dismissing several ministers.
She won a second term in 2011 elections and tackling graft is still one of the most pressing issues in the country a decade after the end of war.
Ms Gbowee added Monday: "In her first term she developed infrastructure. But what good is infrastructure if people don't have enough to eat?"
"Development in a land of hungry, angry people is nothing. When they get angry, they will burn it down because it is not connected to a large section of the population."
In June the International Crisis Group released a report warning that corruption, along with nepotism, impunity and unemployment, could "jeopardise Liberia's democracy."
Ms Gbowee, who staged peace protests to bring a halt to Liberia's war with a quirky mix of prayer and a sex strike – urging women to shun sex with their partners – said she was "under a lot of pressure to say more and do more" to correct the state of affairs in Liberia.
"Every day I get telephone calls. They say 'do something, do something."