Suu Kyi, who was released in 2010 by Myanmar's military rulers after years under house arrest, said that she believed there had been voting irregularities, illegal activities and intimidation either committed or encouraged by official entities.
But Suu Kyi, a pro-democracy figure and Nobel Peace Prize laureate, said at a news conference outside her residence in Yangon that she did not "at all regret having taken part" because the election campaign had raised political awareness among Myanmar's population.
Worldwide attention is focused on the April elections, which are seen as a test of the Myanmar government's commitment to removing the fear and paranoia of citizens silenced by nearly five decades of military rule. The government has invited in hundreds of foreign journalists and election observers to witness the voting.
The vote, in which credible alternatives to the ruling party will appear on the ballot, was called to fill seats vacated by the promotion of parliamentarians to the Cabinet and other posts last year. Suu Kyi's party, the National League for Democracy (NLD), is in competition for 44 of the 45 seats up for grabs in the by-elections. It had boycotted previous elections.
Its candidate in one constituency has been rejected by the election commission because his parents had taken up foreign residency, Suu Kyi said, adding that the party planned to challenge the candidate's exclusion later.
The international community has applauded recent steps toward greater openness in Myanmar, also known as Burma, long secluded from the rest of the world after a military junta grabbed power in 1962. The generals are loosening their grip after international sanctions and criticism over their regime's human rights record.
So far this year, the regime has agreed to negotiate with an ethnic rebel group and pardoned hundreds of political prisoners. Top diplomats from the United States, Britain and France have made recent visits to the country after decades of shunning it.
Suu Kyi said she believed President Thein Sein, a former general who has taken civilian office, wished for democratic reform, but that she was uncertain how much support he had, notably from the military.
She told the hundreds of journalists gathered outside her residence Friday that she didn't plan on becoming a minister in the military-backed civilian government, if a position was offered to her. Under Myanmar's constitution, lawmakers can't hold ministerial office.
Asked where she would place Myanmar's democracy on a scale of one to 10, Suu Kyi quipped, "We're trying to get to one."
She mentioned two recent physical attacks against NLD candidates, which she said she thought were actions of individuals rather than state-sponsored acts.
In one of the attacks, somebody used a catapult to fire betel nuts at a candidate's car, she said. Some people in Southeast Asia chew betel nuts as a mild stimulant.
The daughter of Gen. Aung San, a hero of Burmese independence, Suu Kyi herself became an inspiration with her long struggle for democracy in the country.
She quietly defied Myanmar's military junta for years from from the prison of her crumbling Inya Lake villa in the former capital, Yangon.
Suu Kyi, 66, is now a candidate for the parliamentary seat in Kawhmu, a contest analysts say she is all but certain to win. Results are expected about a week after the voting.
Suu Kyi has been crisscrossing the country to attend election rallies where she is often greeted like a rock star. But her busy schedule has taken its toll: earlier this week she had to suspend campaigning after falling ill.
On Friday, she said she felt somewhat "delicate," but was in good enough spirits to joke about her health.
She told the reporters at the news conference that if they asked "any tough questions, I'll faint straight away."