The country's Constitution has "clearly defined the responsibilities and functions of national institutions" and it is incumbent on them "to perform their duties within constitutional limits", Kayani said while delivering an address at an event marking the army's Youm-e-Shahada (Day of Martyrs).
In an apparent reference to Prime Minister Yousuf Raza Gilani's conviction of contempt by the Supreme Court for refusing to act on orders to revive graft cases against President Asif Ali Zardari, the army chief said the prime objective of the democratic system is to "ensure the welfare, happiness and increased dignity of the people and the establishment of a balanced society where every person can get justice equally".
"This is the only way which can further strengthen Pakistan's national security," he said during the late night ceremony to honour soldiers killed in the line of duty and while fighting extremists.
The military, he said, believes in a "strong democratic system and its continuation". At the same time, Kayani touched on the national security situation and said Pakistan is "still in a state of war" despite unprecedented sacrifices made by the people and security forces in the campaign against terrorists and extremists.
The Pakistan Army, Frontier Corps, Pakistan Rangers and police had "achieved successes in many difficult areas while fighting against extremists and terrorists" while the people's sacrifices and steadfastness had boosted the morale of the armed forces.
"I am hopeful that we will emerge from this stage victorious with the help and prayers of the nation. We will be successful when we have a strong belief in the ideology of Pakistan. Any doubt about this ideology would weaken the country," Kayani told a gathering that included top Pakistani military officials and defence attaches from different countries.
The army chief also referred to the unilateral American raid in Abbottabad that killed Osama bin Laden and a cross- border Nato air strike that left 24 Pakistani soldiers dead in November last year and said: "some foreign elements had launched a campaign of mistrust" despite the sacrifices made by the Pakistani people and armed forces.
This campaign "pushed the entire nation into a psychological crisis and forced the nation to review relations with others", he said.
"We think that others will have to keep in mind our sovereignty, pride and honour," he added.