The premier backed the decision to introduce martial law, saying it could help the proposed election take place, and added that the government would "engage in reforms before the election" -- without giving further details.
Anti-government protesters bidding to topple Niwattumrong's government have said there cannot be a new election without loosely-defined reforms targeting the dominance of billionaire former premier Thaksin Shinawatra.
A February 2 poll was annulled by the courts after protesters widely disrupted the voting.
The government and army will hold talks "likely to be this week", added Niwattumrong, who replaced Thaksin's younger sister Yingluck as premier after she was ousted by a controversial court ruling on May 7.
Protesters say the hobbling government lacks legitimacy and are pressing for the upper house of Thailand's parliament, the Senate, to trigger a legal mechanism to wipe out the government and appoint a new premier.
A group of 25 senators on Tuesday sent a petition to the Consitutional Court to rule on the status of the remaining cabinet members.