"The President, the Prime Minister, and a majority of legal and constitution experts believe that there is no need for the referendum from the legal point of view," Seks was quoted by the commercial television network "Nova TV" as saying on Tuesday evening.
Seks said the latest surveys had shown a considerable rise in public support for Croatia's plans to join the alliance, and assessed that Croatia would enter NATO sooner than the European Union.
"With the admission to NATO, Croatia will not get obligations, and it will decide independently in its parliament about everything," the parliament chief said.
He also wanted to persuade citizens not to worry about any military bases on the Adriatic or about the deployment of Croatian soldiers to NATO-led missions.