Gotovina, 50, Croatia's most-wanted war crimes suspect, was arrested in Spain last week after four years on the run. He is charged by the International Criminal Tribunal for the former
Yugoslavia (ICTY) with committing atrocities against ethnic Serbs in 1995 and faces life imprisonment if found guilty.
Gotovina, who was taken into custody by the tribunal on Saturday, has 30 days to enter a plea. But Luka Misetic, his lawyer, said: "At his first appearance [scheduled for
Monday at 1145 GMT], General Gotovina will plead not guilty."
Misetic said Gotovina was "relaxed and self-confident". No date for his trial has been announced.
The indictment has been a cause of diplomatic tension for years. The operation in August 1995 that led to the charges against Gotovina practically ended Croatia's war of independence from the former Yugoslavia, and he is as a national hero to many Croatians.
In the coastal town of Split on Sunday, thousands of nationalists chanted "Treason!" and denounced the government during a protest against Gotovina's arrest.
Many of the 50,000 demonstrators waved Croatian flags, photographs of Gotovina and banners insulting the authorities and Carla Del Ponte, the chief UN war crimes prosecutor.
To many Croatians, Gotovina is
still a national hero
Gotovina faces charges relating to the death of about 150 ethnic Serb civilians during a Croatian offensive in the Serb-held Krajina region.
According to the indictment, Croatian forces under Gotovina went on a rampage of persecution, murder, plunder of property, destruction of towns, deportation and inhuman acts.
He faces three counts of crimes against humanity and three of war crimes.