Sungai Siput MP and 13 others were engaged in a peaceful assembly outside the Perak state assembly to highlight the plight on landless villagers.
The state assembly was in session when the arrests took place. The police said the protesters were arrested for failing to disperse after taking part in an illegal gathering.
The protesters had gathered to highlight the plight of Kampung Dewan Bandaraya Ipoh who have not been granted land titles for more than 10 years.
The residents want the BN-led government to sort out their land titles issues as soon as possible.