The announcement came after supporters of the peace deal marched in the country's capital, Bogota, after it was rejected by a majority of Colombians in a referendum earlier this month.
Colombian President Juan Manuel Santos has extended a ceasefire with the Revolutionary Armed Forces of Colombia, or FARC, until the end of the year to gain time to reach a final accord with the left-wing rebel group.
The decision came after thousands of people took to the streets in the country's capital Bogota on Wednesday to demand the government rescue the peace deal, which was rejected by a majority of Colombians in a referendum earlier this month.
"One of the students reminded me that in the army and in the guerrilla ranks, there are young people waiting to see what happens, hoping that they don't need to fire another shot," Santos said in a televised address on Thursday.
"For that reason, and at the request of the students, I have taken the decision to extend the ceasefire until 31 December."
Santos won the Nobel Peace Prize last week for his efforts to end over 50 years of conflict with the FARC, in which more than 260,000 people have been killed.
The Colombian president announced on Sunday that he would donate the prize money he received to victims of the conflict.