Pukanic, 47, died alongside Niko Franjic, his marketing chief, in a car bomb attack at his newspaper offices in the centre of Zagreb, the capital, on Thursday.
"We will introduce extraordinary mobilisation measures," Sanader said. "We shall deal thoroughly with organised crime, mafia or terrorism. Croatia will be a safe country."
Jasna Paro, a Croatian broadcaster, said: "This terrible murder happened just a day after the prime minister in parliament won the support of all parties on imposing the higher measures and tightening the laws on security and on organised crime in the country.
"So I think everybody in the country would consider this murder a message, not only to the politicians, but to everybody that those who are behind the murder are serious and dangerous people."
Hannes Swoboda, the European Parliament's rapporteur for Croatia, said Croatia's rising crime could affect its EU application for accession in 2011.
"I think the government's negligence towards organised crime and corruption has to stop ... and ... Sanader must personally take measures against organised crime."
Two other people were injured in Thursday'sattack, which follows a number of violent events in the city in 2008.
Two weeks ago the 26-year-old daughter of a prominent lawyer was shot twice in the head in Zagreb. Officials called the death a mafia-style slaying, but no one has been arrested over the attack.
A well-known crime reporter was also attacked on the street and a city administrator beaten with a baseball bat earlier this year.
The incidents have been met with indignation by locals and allegations that the state cannot deal with crime.