Santos Sunday said that if FARC continues its offensive against oil infrastructure, it could jeopardise the ongoing peace talks in Havana, Xinhua reported.
Last week, FARC leader Rodrigo Londono ruled out the possibility of reaching a peace agreement with the Colombian government by this year, at a time when the president has criticised the rebel group for dragging its heels.
"We must accelerate, because the sooner we reach the end of the conflict, the more lives we will save," Santos said.
The meeting is scheduled to be held Friday.
A delegation of victims of the internal armed conflict met in Havana with FARC representatives, who offered their apologies, in a development highlighted even by the UN.
The Colombian government and FARC started the peace process in Dec 2012 in Cuba but has not come to any conclusions as yet.