Mr Thawil said on Tuesday he would pursue peace talks with insurgent groups under the present government's policy.
However, he was of the opinion that talks were not always a way out; that there were also other methods of solving problems.
He said he would continue the work that has been left incompleted since he was moved from the NSC post.
A royal command was issued and published in the Royal Gazette on Monday, officially reinstating him as NSC chief.
He said it was not necessary for him to report to caretaker Prime Minister Yingluck Shinawatra on returning to the NSC office, or for Lt Gen Paradorn Pattanatabut to formally hand over the responsibilities to him.
Mr Thawil also said he did not worry about working with the government, because he believed in his professionalism.
Whether he would allowed to attend cabinet meetings was for the government to decide.
He said there is no law requiring him to be part of the operations of the Centre for the Administration of Peace and Order (Capo), but he would be glad to do so if asked.
In handling mass demonstrations called by the United Front for Democracy against Dictatorship (UDD) and the People's Democratic Reform Committee (PDRC), Mr Thawil said the NSC would coordinate intelligence operations with police.
On a summons issued by the Department of Special Investigation (DSI) for him to hear charges in connection with his appearance on the PDRC stage, Mr Thawil said he had assigned his lawyers to explain that he was excercising his rights under the constitution and he had not broken any law.