In a speech from a central square in Kiev, Viktor Yushchenko said all the country's politicians should be able to speak Ukrainian.
Twenty-four percent of the population in Ukraine, which is marking the 15th anniversary of its secession from the Soviet Union, speak Russian, particularly those living in the east of the country, near the Russian border.
"The principle of this country is simple - a Ukrainian citizen is free to choose," Yushchenko said. "But a Ukrainian politician or a public servant must know, use and live by the national language."
Yushchenko also called for an end to religious debates. Ukraine's two leading religions are Catholicism dominating in the west and Orthodoxy in the east.
The president also said he advocated independence and international recognition for the Ukrainian Orthodox Church.
Following Ukraine's independence in November 1991, Metropolitan Filaret, then head of the Ukrainian Orthodox Church, convened a national church council and declared the canonical independence of the Ukrainian church from Russian.
The council later asked Alexy II, the head of the Russian Orthodox Church, to approve the decision, but it was rejected in April 1992, and the Russian church went so far as to anathematize Filaret.
The Kiev Patriarchy has not been recognized by any of the world's Orthodox churches.
Yushchenko also called for a nationwide discussion aimed at historical reconciliation and mutual understanding between the eastern and the western parts of the country.
The split in Ukrainian society became particularly evident during the past 20 months of political turmoil, when candidates backed by the east and west of the country vied for power. The country emerged from the political wrangling with a pro-Western president, Yushchenko, and a new prime minister, Viktor Yanukovych, backed by eastern Ukrainians.
The Ukrainian leader further said he expected parliament, the Supreme Rada, to adopt a bill declaring the famine of 1932-33, or "holodomor", an act of genocide against the Ukrainian nation.
The famine, which claimed millions of lives, is said to have been deliberately orchestrated by the Soviet authorities under Joseph Stalin to destroy Ukrainian society and culture in order to subdue the nation.
Yushchenko instructed the government to set up a memorial to the victims of the famine by the 75th anniversary of the tragic events.
The fourth Saturday of November is the day of commemoration of the famine victims in Ukraine.
