Members of the al-Mutair tribe descended on the headquarters of parliamentary candidate Mohammad al-Juwaihal, fought with his supporters and set his tents ablaze in Adailiya late Monday, Gulf News reported.
The protesters criticized the candidate and called for him to be barred from running in the elections Thursday.
Al-Juwaihal, running in the Third Constituency, had insulted Abaid al-Wasmi, a candidate in the Fourth Constituency and member of the al-Mutair, the Arabic daily al Qabas reported.
Al-Juwaihal was quoted as saying: "Al-Wasmi described Kuwaitis as dogs, and I tell him that he is the son of 60. And if he thinks that his tribe will protect him, we will crush you and your tribe."
After setting ablaze the tents, tribe members prevented fire brigades from reaching them to extinguish the flames.
Al-Wasmi was reported to have handed a formal complaint against al-Juwaihal to the interior minister.
About 400,000 Kuwaitis are expected to vote Thursday to elect 50 members of Parliament.