Bangkok will be under close watch, while police will be asked to regularly inform the public of any situations, she said.
The premier spoke after being interviewed about an incident where a bomb-like object was found at Bang Khen Railway Station in Bangkok on Saturday morning. She was not informed of all the details, she said, but was aware the item was in fact a hoax bomb made of money box or piggy bank.
On Thursday night, six bombs were found in three locations of Bangkok and later defused by a bomb squad. One suspect was arrested.
Ms Yingluck asked members of press and media not to disseminate information if it was not official from the police.
When asked if the public could be assured of their safety before the New Year celebration, the prime minister said that authorities will work at their full capacity to monitor the situation.
Officials will investigate to find a solution to the recent bomb cases in the capital as quickly as possible and whether there may have been other persons involved in committing the wrongdoing along with the apprehended suspect, she added.