The body of Alessandro Parini, a 35-year-old Rome resident, is expected to return to Italy on Tuesday.
No bullets were found in his body.
A car accident was ruled out, according to the investigators, who said the driver, Israeli Arab Abu Jaber, acted in a "premeditated way".
Israeli doctors have ruled out that he suffered a stroke while driving the vehicle.
"The more we investigate, the more we come to the fact that it was an attack motivated by nationalistic reasons," a police spokesman said.
Jaber is believed to have acted in retaliation for Israeli attacks on Palestinians.
Politicians in Italy and Israel earlier expressed shock and condemnation after Parini was killed amid a spiral of violence.
Foreign Minister Antonio Tajani said two other Italians were among seven people injured in the attack, in which the assailant rammed the car into people walking on the sea front.
The injured Italians are not seriously hurt.
Italian President Sergio Mattarella on Saturday expressed "execration" at the attack, describing it, in a statement, as a "cowardly act of terrorism".
He said he sent "the Republic's and his own personal sentiments of condolence and closeness to Parini's family and friends".
He also expressed the condolences of the Italian Republic to the President of Israel, Isaac Herzog.
Also earlier on Friday, Italian Prime Minister Giorgia Meloni expressed her "deep condolences" and "closeness" to the victim's family and those who were injured.
She also voiced "solidarity to the State of Israel over the cowardly attack".
Israeli Foreign Minister Eli Cohen, meanwhile, voiced his country's condolences to Italy.
"On behalf of the government and the people of Israel, I send our deepest condolences to the family and friends of Alessandro Parini, the Italian citizen who was murdered in yesterday's terror attack in Tel Aviv, and to the government and the people of Italy," Cohen said via Twitter on Saturday.
"Murderous terrorism is the enemy of us all.
ANSA
