The sale contract gives the Slovene company the exclusive right to transport the factory's products.
Local police had to regulate traffic on a road leading to the factory because the protesters obstructed traffic on it.
A representative for hauliers from Sibenik, Zoran Cevid, said the protest was staged spontaneously because local hauliers feared that they would no longer be hired for transport jobs.
He said he expected about 30 other hauliers to join the protest during the day and that the government would voice its position on the matter and annul the sale contract.
The representative of road hauliers at the Croatian Chamber of the Economy, Ivan Knezovic, said that Croatian road hauliers would go on a general strike on September 5, which he said would completely block the passage of goods in the country.
The coordinating body of associations gathering road hauliers announced a news conference in Zagreb for Friday.