The president's order came in a weekly meeting with his presidential aides.
The move is apparently aimed at pressuring the opposition parties to come to the dialogue table as they, especially the main opposition Liberty Korea Party, had been boycotting discussions on a constitutional change.
"As I have repeatedly said before, I will do my utmost as the president to keep my promise to the people to hold a vote on a constitutional amendment concurrently with the June local elections," the president told the meeting, according to Cheong Wa Dae pool reports.
"It is fortunate that each party recently confirmed their efforts to amend the Constitution and the ruling and opposition parties begin their consultations. However, it is deplorable that there still only exist the basic principle and direction and no concrete progress. I once again urge (the parties) to be more responsible and engage in consultations to come up with a bill on a constitutional revision," he added.
A Cheong Wa Dae official explained the government will still wait for the rival parties to come up with a joint proposal.
"This only means the government will have its own proposal ready just in case, and it does not mean the government will actually exercise its right to legislate," the official said, speaking on condition of anonymity.
Moon noted it was best for the parliament to come up with a proposal but said the government will field its own bill should the rival parties fail to reach an agreement in time.
"It will be the best for the National Assembly to reach a consensus based on the people's wish, but I believe the current condition does not allow us to wait for a parliamentary agreement. Now the president cannot but begin preparations for a constitutional amendment by gathering the people's opinions," Moon said.
The president earlier said a stand-alone vote on a constitutional amendment will cost an additional 120 billion won ($110 million) in government spending. He has also noted the rival parties will need to come up with a joint bill at least before the end of March if the bill was to be put to a vote in the local elections, slated for June 13.(Yonhap)