"I swear to God, I am not going to pardon (him)," she was quoted as saying on Monday by the official Andina news agency, as she campaigned ahead of a June 5 run-off vote against nationalist rival and ex-military man Ollanta Humala.
"I have repeated several times that it is neither my intention, nor the intention of my family, to pardon Alberto Fujimori," she said.
Keiko Fujimori has in the past been critical of her father's government, in which she served as First Lady after he stripped her mother of the title.
"I condemn the errors that occurred under my father's government, and I salute the positive actions. I think we should look at the past objectively and without rancor," she said.
Humala -- who won the first round with 31.7 percent of the vote, compared to 23.5 percent for Fujimori -- has meanwhile denied allegations that left-wing Venezuelan President Hugo Chavez is financing his campaign.
"My candidacy is financed by the Peruvian people," he told CNN International, after a conservative rival had earlier accused him of accepting funds from Caracas without providing any evidence for the allegation.
Humala, 48, said he had submitted all the relevant campaign finance documents to the national election commission.
The Peruvian government has vowed to remain neutral in the presidential polls and to ensure an orderly transfer of power.
Humala ran for president in 2006 but lost after criticism of his close ties to Chavez. He now claims to have changed and denies ties to the Venezuelan leader, the region's leading anti-US figure.
Keiko Fujimori, 35, favours free-market policies, but is mistrusted by many because her father -- president from 1990 to 2000 -- is in jail for corruption and human rights crimes committed during his crackdown on leftist guerrillas.