"The parliament has surprised us with... (a law) that copied the laws of the pre-political reform dark age. It is a backward move," said nine political associations in a statement on Thursday.
"This law is unconstitutional. It contradicts the content of the National Act Charter and breaches... the universal declaration of human rights," it added.
The details of the new law, which was passed in the parliament on Tuesday but needs to be ratified by King Hamad following examination in the appointed Consultative Council, have not been published as yet.
But political groups - which operate in Bahrain as associations due to a ban on political parties - said it introduces many restrictions.
"The new law banned what we demanded of foreign funding for training purposes, while MPs themselves receive foreign funding for such purposes and (to cover cost of) attending forums (abroad)," the president of National Democratic Act Association, Ibrahim Sharif said.
He criticised a clause in the new law which increases the minimum age required to join political association from 18 years old to 21, describing it as "controversial".
"If an 18-year-old person is punishable by law, and could be sentenced to death...how could he not join a political association"
National Democratic Act Assn.
"If an 18-year-old person is punishable by law, and could be sentenced to death...how could he not join a political association," he questioned.
"According to the new law, we also will not be allowed to express our opinion as a political association in any Arab or international affair... Any contact with foreign countries will be in the hand of the minister who decides when and how we contact other countries," he said.
Bahrain allowed political groupings in 2001 to establish political associations. Tens of these associations operate in the small Gulf kingdom representing Sunni and Shia Islamists, as well as liberals, leftists and Arab nationalists.