The deposed monarch said he did not want to be active in the country's politics, but did want a largely ceremonial role. He said that the political parties would have to answer for their behaviour.
His comments come amid a political vacuum, with political parties failing to reach agreement on a new Constitution and fresh elections planned for November.
The former king, who celebrated his 66th birthday yesterday, also said that he had been forced to make an agreement with Nepal's opposition parties following anti-government protests in 2006 that he would be a constitutional monarch.
"This included the reinstatement of the dissolved parliament, the appointment of a prime minister from among the parties, and restoration of constitutional monarchy and multi-party democracy," the BBC quoted Gyanendra, as saying.
Criticising the Parliament for failing to promulgate a Constitution, Shah warned that monarchy could return if the people wanted.
"Monarchy may comeback if Nepalese people wish," Shah said.
"Country was suffering due to failure of the Constituent Assembly to deliver a constitution," Shah added.