"Yatsenyuk demanded in the name of Maidan that Yanukovych resign," the lawmaker said in reference to the mass anti-government protests that have been raging on central Kiev's Independence Square since Yanukovych rejected an historic EU trade deal in November.
"Yanukovych promised to put it in writing and we are waiting for him to do so," Katerynchuk said.
Rumours of the embattled leader's imminent departure from power have swirled around Kiev since Yanukovych and three top opposition leaders signed a deal on Friday aimed at ending Ukraine's worst crisis since its post-Soviet independence.
The peace pact shifts most political powers toward parliament and away from the presidency. Yanukovych also agreed to move forward March 2015 elections to December and quickly appoint a new coalition government.
But the protest movement has radicalised considerably in the days since the police first opened fire against protesters in the heart of Kiev on Tuesday night.
Yanukovych left Kiev late on Friday for the industrial eastern city of Kharkiv -- a bedrock of the president's pro-Russian support.
A spokeswoman for the president told AFP that Yanukovych was planning to meet voters in Kharkiv and make a local television appearance.
But she denied to Ukrainian media that Yanukovych intended to resign.