In a statement in the capital Damascus on Tuesday, the parties said: "The leaders of the Kurdish parties decided unanimously to continue their political activities, which are a natural and national right, necessary to Kurdish progress in Syria."
Earlier this month, Syrian security services told the Kurdish groups their parties were illegal and their political activities prohibited.
But the Kurdish groups say their parties "are legitimate because they represent over two and a half million Kurds in Syria who suffer under policies that go against international rules and charters."
They said the decision was a setback to positive steps taken recently by President Bashar al-Asad, who has insisted the Kurdish community is an important part of Syria.
The ban also came despite the fact that ethnic Kurdish leaders had tried to end deadly confrontations between members of the community and the security forces in mid-March
At least 25 people were killed in clashes over six days. Kurdish groups said the authorities also detained about 2,000 people.
Analysts have said the ban is an effort by the ruling Baath party to crush democratic movements that have emerged since Asad came to power in July 2000 after the death of his father, Hafez al-Asad.
Most Kurds in Syria live in the north near the Iraqi border.
Many refused to register in the 1962 census to avoid military service, which has since prevented them, and their descendants, from obtaining Syrian nationality.