Thousands of people took to the streets to protest against the decision and chanted "No to the pardon!"
The police clashed with the demonstrators with the help of tear-gas and water cannons.
Fujimori was sentenced to 25 years after he was convicted of corruption and human rights violation charges in 2009.
A medical panel determined that Fujimori had a progressive, degenerative and incurable disease and the jail conditions presented a grave risk to his life and health. He was rushed to the hospital on Sunday due to low blood pressure, shortly after his release from the prison.
The decision has triggered several outrageous protests across the country as the former president is seen as a deeply divisive figure and a corrupt dictator by the public in Peru. (ANI)