"The best way to avoid war is preparing for it"
Chavez has said that US access to the Colombian bases poses a direct threat to his oil-exporting country.
But Washington and Bogota say the deal is aimed solely to create a joint force to fight drug cartels.
During his weekly radio and television show, Chavez warned that if war broke out with Colombia, the conflict could "extend throughout the whole continent", adding that Venezuelan citizens should be ready to "defend the homeland".
"Let's not waste a day on our main aim - to prepare for war and to help the people prepare for war, because it is everyone's responsibility," he said.
"The best way to avoid war is preparing for it."
Chavez has repeatedly voiced deep concerns over what he says is US encroachment in the region.
The Colombian government denies it is acting aggressively, after a series of shootings and other incidents along the border raised tensions in recent weeks.
"Colombia has not made nor will it make any bellicose move toward the international community, [and] even less so toward fellow Latin American nations," Alvaro Uribe, the president, said in a statement.
"The only thing we are interested in is defeating terrorism related to drug trafficking, which has been so unfair to Colombians for so many years."
Last week Chavez ordered 15,000 soldiers deployed along the border saying increased security was needed to meet the rising violence.