Among those in attendance were Prime Minister Ivo Sanader and Deputy Parliament Speaker Mato Arlovic.
"I expect the state authorities to be more active in restructuring the economy and to create conditions for the increase of the annual Gross Domestic Product to five per cent and more. This is a condition for increasing employment and the standard of living," Mesic said in his address.
He underlined that 25 June 1991, when the Croatian parliament adopted a declaration proclaiming Croatia's sovereignty and independence, was one of the most important dates in Croatian history.
Mesic said the 15th anniversary of that date was being celebrated alongside anniversaries of the creation of the Croatian army and the first Homeland War victories. He thanked everyone who had taken part in the defence and liberation of independent Croatia.
"This year's celebration is taking place also in the year in which we actually began negotiations on future membership of the European Union."
Mesic said the negotiations called for legislative adjustments, home and foreign policy tasks and reforms of the judiciary, health and education.
The president said Croatia had made significant headway which he expected to be acknowledged by Euro-Atlantic structures. He added, however, that EU and NATO membership was not only a political decision but also a matter concerning all citizens.
Mesic said that due to poor demographic trends, an active population and family policy should be one of the main concerns of the current and every future Croatian government.
"The tasks are many, but we do not have a right to exhaustion, apathy or indifference," said the president, adding that the successes of the past 15 years were indeed historic.
"Therefore, I look upon the future with optimism, I believe in the success of our endeavours," he told the 200 gathered at the reception.