Opposition groups warned on Tuesday that any attempt to amend the electoral law to impact poll results could destabilise Kuwait and undermine relations with the ruling family.
A statement signed by almost all opposition groups also cautioned that Kuwait, an OPEC member and the first Gulf Arab state to embrace democracy in 1962, was becoming increasingly autocratic.
"The current intentions of the political authorities... could severely undermine political stability and the historical relations binding the people with the Al-Sabah ruling family," they said.
The Al-Sabahs have ruled the oil-rich emirate unchallenged for more than 250 years. The emir, crown prince, prime minister and key cabinet ministers are all from the ruling family.
The opposition said government's plans to amend the electoral constituency law was aimed at reducing their chances of retaining a majority in the next parliament, as in the house scrapped by a court on June 20.
It also criticised the government for issuing legislation in decrees by the emir after dissolving parliament on Sunday, charging that this was an attempt to bypass the public's supervision.
"Kuwait yesterday entered a new phase of autocratic rule that does not believe in democracy or popular participation after the cabinet passed a group of decrees... without any regard for the people," the statement said.
The opposition was referring to four draft legislative bills passed by the cabinet and to be issued by Emir Sheikh Sabah al-Ahmad al-Sabah in emergency decrees after the parliament's dissolution.
The opposition said the move was a prelude to another decree on amending the electoral constituency law in order to change the voting system in such that would enable the government to control the next parliament.
Under the constitution, the emir can issue legislation in the form of decrees in the absence of parliament, but the opposition says this authority is limited to urgent matters that cannot wait for parliament to meet.
On September 25, the constituency law was confirmed as constitutional by the emirate's top court.
Kuwaitis are scheduled to go to polls within two months for the fifth time since mid-2006.
The Gulf state has been rocked by a series of political crises since 2006 during which the government resigned nine times and parliament was dissolved on six occasions, five of them by the emir and one by court.