"This is against the law and we will appeal the IHEC's decision ... at court to prevent those candidates from entering parliament," he said.
Lami declined to identify the candidates or say which parties or coalitions they belong to.
He said a final decision on whether to bar them would be made by a judicial committee before the results of the March 7 election are certified by a federal court.
'Politically motivated' move
The Iraqiya bloc rejected the the commission's claims and said that all of Iraqiya's candidates had previously been approved.
"The decisions of the Accountability and Justice Committee are not legal," Hamid al-Mutlaq, a winning candidate on the Iraqiya list, said.
"Those six winning candidates have the approval of [the election commission] and this decision is a political one, not a legal one."
The State of Law coalition of Nouri al-Maliki, the prime minister, and Allawi's cross-sectarian bloc finished just two seats apart and a successful challenge to any of the Iraqiya candidates could shift the balance of power.
The former prime minister already faces an uphill struggle to form a government as State of Law and the third-place finisher, the Iraqi National Alliance (INA), have said they are in talks to form the largest bloc in parliament.
Maliki has also repeatedly said that he will not accept the results of the election and has demanded a full manual recount.
Lami's panel, which replaced a de-Baathification committee set up to purge Saddam loyalists from government after the US invasion of Iraq in 2003, barred more than 500 candidates from the parliamentary vote in the weeks before the election.
The ban infuriated many of Iraq's minority Sunnis, who dominated the country for more than two decades under Saddam, despite it containing more Shias.