"I expect cooperation and support from everybody to institutionalise the federal democratic republic system in the country," Khanal said in an address to the nation, which was televised live.
He called on all political parties, including Nepali Congress (NC), to join the government.
He also sought cooperation from all sides in accomplishing the task of drafting a new Constitution and completing the peace process on time.
Khanal is yet to give a full shape to his government and divide portfolios to ministers due to the CPN-UML`s failure to strike a power-sharing deal with the Maoists, on whose support Khanal became Prime Minister.
All the democratic and revolutionary forces should join hands in this transitional phase, Khanal said.
The Prime Minister also asked civil servants and security agencies to fulfill their duty with full dedication without giving rise to any doubt.
Earlier in the day, Khanal held discussions on key issues relating to formation of the government with Maoist chief Prachanda at his official residence at Baluwatar.
After the meeting, Prachanda said his party would continue its support to the government, but made it clear that Maoists cannot join it till the government implements a seven- point agreement reached with them.
Prachanda also said the delay in the Cabinet expansion was caused by internal differences within the CPN-UML.