The commission began its first hearings in East London on Monday.
In a statement in Durban, Buthelezi said after careful consideration the IFP had decided it was impossible for it to receive impartial treatment by the commission.
"As a consequence, and regretfully, we have concluded that the IFP will play no role in the truth commission's hearings, questioning or deliberations.
"The IFP, however, recognises and supports the rights of individual party members to appear before the commission in their personal capacity."
Buthelezi said about 12000 IFP members and about 430 of its leaders had been murdered in the past decade, therefore the IFP had "as much interest as any party in reaching the truth of South Africa's recent history".
"Our concern is not the truth emerging, but whether the whole truth will emerge."
Buthelezi said the IFP was the victim of a so-called "people's war" conducted by the former United Democratic Front, the African National Congress and its allies against the IFP and the people of KwaZulu-Natal in particular.
"It is important that history records the pogrom against elected black leaders and councillors in KwaZulu-Natal and the campaign of assassination against traditional structures in this and other provinces, a campaign which continues today."
The IFP said it was important that evidence on the ANC's alleged detention, torture and murder of its own members in so-called detention centres be heard and the perpetrators be held accountable.
"To these ends the IFP intends with immediate effect to compile and publish in the public arena a dossier detailing the ANC's war against the IFP and the people of KwaZulu-Nataland other provinces, as well as that party's gross violations of human rights carried out against its own members over a 12-year period."
This information would be presented to the truth and reconciliation commission, the IFP said.
The IFP also questioned recent appointments to the commission.
"We have noted that (commission chairman) Desmond Tutu is himself a former patron of the ANC's internal front the UDF, and that the commission's chief of investigations, Lawandhle Magadhla, is the former head of the ANC's department of intelligence and security (Mbokodo) in KwaZulu-Natal.
"We have also noted that the commission's new national director of investigations, Glenn Goosen, is a long-time Nusas (National Union of SA Students), UDF and ANC activist," the IFP said.
"In these circumstances ... the IFP has decided that it is impossible for us to receive impartial treatment before the commission.
"As a party we remain fully committed to the process of reconciliation in South Africa.
"We are saddened that a genuine attempt to foster a balanced understanding of our recent past has been missed, being usurped by a process of historical cleansing reminiscent of show trials of the Eastern bloc," the IFP said.