In a separate interview with local radio, Rivera said that government forces knew where Cano is hiding.
He is "fleeing from the security forces. He has no rest... we are not going to let up," he said.
After taking office, Santos said he would not close the door to talks, but they would have to be "based on the unalterable premise that (the guerrillas) give up arms, kidnapping, extortion, drug trafficking, and intimidation".
The Farc has an estimated 8,000 fighters. Another leftist rebel group, the National Liberation Army, is believed to have some 2,000 fighters.
Colombia has been beset for years by violence involving leftist guerrillas, right-wing paramilitary death squads, and powerful drug cartels.
Santos said on Friday that he did not believe the conditions were ripe for talks with the Farc, and ordered Rivera to press ahead with an offensive against them.
As defence minister, Rivera is in charge of both the armed forces and the national police.