Stephen Keshi's men enter the showpiece on the back of four winless friendlies, the last of which, against the United States, ended in a 2-1 defeat.
But Maigari has called for calm, insisting Nigeria have a great chance in Group F having been handed Bosnia-Herzegovina, Iran and Argentina as their opponents.
"I want to assure Nigerians at home and in the diaspora that the Super Eagles will not disappoint in Brazil," said Maigari.
"For sure, our people would have wanted the team to win the matches against Italy, Mexico, Scotland, Greece and USA. But we drew the first four and lost the last one.
"I have spoken with the head coach and he is optimistic that his boys will be ready for the finals.
"The earlier draws, and the loss to (the) USA have afforded our boys a lot of lessons, which will be useful against Iran in the first match and subsequently.
"I have confidence in the team. From what I saw at the final training camp in USA, I believe the African champions are set to do Nigeria and Africa proud at the FIFA World Cup."
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