"My hopes over a successful execution in this process have been increased," Abdullah Ocalan said in a message relayed on Tuesday by pro-Kurdish lawmakers who visited him in his prison on the island of Imrali near Istanbul.
He said "we have entered a new phase as of October 15 regarding the process that concerns Turkey's democratic future".
The PKK, which has waged a bloody, three-decade insurgency for self-rule, had given the Turkish government until mid-October to show it is serious about the peace process.
The peace process had appeared to be making progress, until a standoff over the mainly Kurdish border town of Kobane in Syria which is under attack from Islamic State (IS) jihadists.
Signup to our newsletter and follow us on Facebook and Twitter!
Kurds took to streets earlier this month over Turkey's lack of support for the town, resulting in clashes with police and the deaths of at least 34 people.
Tensions rose further when the Turkish military bombed PKK targets in Turkey last week. The PKK said those strikes "violated the ceasefire" which it has largely observed since March 2013.
Ocalan's call for "restraint" and "calm" ended the protests, which he called a "breaking point" in the peace talks.
"What we need here is trust for peace and democracy, bolder political steps and a clearer will," Ocalan said.