"No weapons or explosives were found. In all, seven persons were arrested and taken for questioning," it said.
Belgium is the EU country with the highest per capita number of fighters who have gone to wage jihad in Syria and Iraq, a figure estimated at 465.
The authorities have tried for years to clamp down on their recruitment, fearing they will return home battle-hardened and even more dangerous.
Belgium has been on high alert since the Paris and Brussels attacks, with investigators believing they were planned and carried out by the same IS cell based in the Belgian capital.