In a statement broadcast on state television, the ministry said the ban had been imposed pending a decision on the dissolution of the RCD party.
The announcement came three weeks after protesters ousted President Zine al-Abidine Ben Ali.
It came amid fresh clashes at the weekend, in which at least three people were killed in separate incidents.
On Saturday police opened fire on protesters in the north-western town of Kef, killing at least two people. Some reports say four died.
On Sunday protesters set fire to a police station and tried to march on the town prison before troops intervened, the official TAP news agency reported.
Sunday also saw clashes in the central town of Kebili, in which one person was killed. It is believed the victim was hit by a tear gas canister.
Correspondents say that if the Democratic Constitutional Rally (RCD) is dissolved, it would be among the most sweeping moves since Mr Ben Ali’s departure.
He fled into exile in Saudi Arabia on 12 January following a month of nationwide anti-government protests. The UN says more than 200 people died in the clashes.
The RCD was the key instrument by which Mr Ben Ali maintained power in Tunisia.
The country is being run by an interim unity government under Prime Minister Mohammed Ghannouchi pending presidential elections due to be held in six to seven months’ time.
Tunisia’s uprising has inspired protest movements elsewhere in the Arab world, including in Egypt.
Source: BBC