Commenting on amendments to the Constitution under which the government will have to report to parliament, the president said: "This will not turn us into a parliamentary republic, and honestly speaking, I think Russia must never become a parliamentary republic, which would be the death of us."
Medvedev said, however, that the constitutional amendments would strengthen the powers of the lower house of parliament, giving the State Duma additional levers to oversee ministerial decision-making.
Medvedev said the inviolability of people's rights and freedoms was more important than the potential reform of the country's political system.
"The Constitution must guard the stability of people's rights, the protection of their rights and freedoms, the fundaments of the system, property rights and justice - these things must not be altered," Medvedev said.
The Duma will hold second and third reading debates on constitutional amendments to increase the current four-year presidential and parliamentary terms to six and five years, respectively, on Wednesday and Friday.
The Duma approved the amendments, proposed by Medvedev on November 5, in the first reading last week.