His denial follows comments by a member of a coordinating committee set up by acting Senate Speaker Surachai Liangboonlertchai, who told reporters on Thursday that Mr Niwattumrong had agreed to meet for talks today.
Mr Niwattumrong said he was not aware of any invitation to attend talks, adding that he had prior engagements in the North over the weekend. The acting caretaker premier was in Chiang Rai yesterday visiting areas and people hit by an earthquake and a series of aftershocks over the past 10 days.
The Senate coordinating committee has invited top government officials, military figures and representatives of public and private organisations for discussions over the past week to find ways to break the political deadlock.
Regarding submitting Sen Surachai's name to His Majesty for royal endorsement as Senate speaker, Mr Niwattumrong said the Council of State, the government's legal arm, must look into it first because complaints had been filed against Sen Surachai.
He said the government must check the legality of the Senate speaker election before proceeding with the royal submission.
Sen Surachai was elected by the Senate as its new speaker last Friday.
The Senate secretariat on Thursday forwarded his name to the cabinet secretariat for submission to the King for royal endorsement.
Singthong Buachum, a member of Pheu Thai's legal team, has filed a complaint with Crime Suppression Division police against Sen Surachai, accusing him of abuse of power and being in violation of Section 157 of the Criminal Code.
Mr Singthong said in the complaint that Sen Surachai, as deputy Senate speaker, had proposed a royal decree for an extraordinary Senate session from May 2-10 specifically to endorse the appointments of an Administrative Court judge and a member of the National Anti-Corruption Commission.
Sen Surachai violated the royal decree by adding the election of a new Senate speaker to the session agenda, Mr Singthong said.