Were the associations formed in Kenya during the colonial period considered as political parties?

Yes and no. Some considered them political parties and others considered them more of a "movement" or "militia" much like the Hutu Militia of Rwanda. Many colonists viewed them as a threat, and thought they were planning to overthrow their rule, so they attempted to squash all organization out of the Kenyans. This in turn made the Kenyans angry and they actually organized a militia which has since grown and joined forces with the Janjaweed.