"The period to August 15 is the heart of the tourism season and an entire week has now been lost," Vassilis Korkidis, the head of the Greek trade association, told state television.
The truckers decided to maintain their protest, ignoring warnings by the government that strikers who continue to defy the law would be prosecuted and that their operating licenses could be forfeit.
George Tzortzatos, the head of the Greek truck owners confederation, told reporters after a union meeting: "We will continue [the strike] in dynamic fashion."
The truckers say that boosting competition in the freight sector by reducing new licence charges is unfair to existing operators ,who have already paid high start-up fees running up to $391,000.
The plan is part of a reform programme that the Athens government committed to in May in exchange for a $143bn loan package from the International Monetary Fund and the European Union.
Greece has suffered waves of strikes and protests over the unprecedented budget cuts and reforms the government had to agree to in order to tap the IMF-EU money it desperately needed to avert default on debts close to 300 billion euros.