When asked who was being targeted among the Cabinet members, Gonzales said it was either himself or Justice Secretary Raul Gonzalez.
The assassination mission aims to pave the way for the setting up of a revolutionary government where key communist leaders will share power with the opposition, he said.
"The communist and some opposition leaders have no option left to bring down the government but to kill the President to attain their political objective," Gonzales told reporters during a press briefing at the Rembrandt Hotel in Quezon City.
Even key opposition leaders, he warned, are being marked for liquidation as well as lawyers and judges to heighten the unstable political atmosphere in the country.
This was why government intelligence operatives have to provide discreet security detail to some of the opposition leaders, Gonzales said.
"We are not watching them, we just want to ensure their safety," he immediately clarified.
Gonzales said government security forces have identified some of the key personalities involved in the plot.
Necessary security measures were already put in place to ensure the safety of the President and other top government officials, he added.
He revealed that deep penetration agents of the government that have infiltrated the ranks of the communist rebel reported that the game plan of the communists was to shift to a series of assassinations in the countryside and then carry out their operation in Metro Manila.
Gonzales said the assassination plan was hatched after communist rebels and their legal fronts failed in their attempt to oust Mrs. Arroyo through people power with the backing of disgruntled soldiers.
Among the failed destabilization tries, he noted, were the series of anti-government mass actions, the failed impeachment bid against the President and the purported attempt of some disgruntled soldiers to carry out a coup.
Gonzales also alleged that the recent series of killings of leftist leaders, journalists and other prominent personalities all over the country are part of the plot to destabilize the government by creating a negative image of the country before the international community.
"The killings are the handiwork of those who want to topple the government," he said.
The national security chief said a similar situation prevailed when Plaza Miranda in Manila was bombed in 1971 and all fingers pointed to former President Ferdinand Marcos whereas, he said, Sison was responsible for the deadly bombing.
He also cited the murders of leftist leaders Rolando Olalia and Lean Alejandro during the early years of the Aquino administration.
"In the case of Plaza Miranda it was Sison who ordered the bombing, and who killed Olalia and Lean Alejandro? They were military adventurists," Gonzales said.
Sison, founder of the Communist Party of the Philippines (CPP), has been in self-exile in the Netherlands since peace talks with the Aquino government broke down in the late ’80s.
As a countermeasure to the alleged assassination mission, Gonzales said the government is now intensifying its legal offensive against the communist movement and their legal fronts all over the country, including the rebellion case against the five party-list lawmakers collectively known as the "Batasan Five" which is pending before a Makati Court.
"We want them in jail," he stressed.
Gonzales clarified that while being a communist is not a crime in the Philippines, their involvement in an armed struggle to topple the government is illegal, thus the full force of the law must be applied to them.
He said the communist party’s legal fronts and its armed wing, the New People’s Army (NPA), are now heavily infiltrated by government agents and every move the rebels make is being monitored. He warned that the government can respond "anytime" to any national security threat.
"We are just watching them, we know their moves."