"Burning election warehouses ... is a plot to harm the nation and its democracy. We will take all necessary measures and strike with an iron fist all who undermine the security of the nation and its citizens," Abadi said in a statement.
"We will take all necessary measures and strike with an iron fist all who undermine the security of the nation and its citizens," he added.
Prior to Abadi's remarks, Iraq's outgoing parliament speaker Salim al-Jabouri said that the fire was intentional and called for a repeat of the election.
Kazem al-Shammari, a spokesman for the Sunni Wataniya alliance, which won 21 seats, was quoted as saying by al-Araby al-Jadeed that "there was no such incident in all previous election cycles, and the fire coincides with the decision to manually re-count the ballot boxes.
The cause of the blaze was not immediately known but a local official said that boxes, part of a manual recount of votes from the al-Rusafa district in eastern Baghdad, had all been scorched.
The ballot boxes are part of a manual recount of votes from the May election, mandated in a law passed by the Iraqi parliament on June 6.
The recount was approved by parliament a day after Prime Minister Haider al-Abadi, whose bloc came third in the election, said there had been serious violations.
