The inflammatory protest was one of a series of religious disputes to hit multicultural Malaysia, where the population is dominated by Muslim Malays who live alongside large ethnic Chinese and Indian communities.
The 12 Muslim Malays pleaded not guilty last September when they were charged with illegal assembly and sedition over the protest, during which the bloodied head of a cow -- a sacred animal to Hindus -- was stamped and spat on.
Defence lawyer Afifuddin Ahmad Hafifi said however that his clients agreed to plead guilty to a lesser charge of illegal assembly when the trial resumed Tuesday.
Two of the group also pleaded guilty to sedition, including the individual jailed for a week, who had been responsible for bringing the cow head to the protest.
"They will serve the sentence. They have pleaded guilty and they are remorseful about what has occurred," the lawyer told AFP.
Prosecutors had previously said their actions were "very serious" and that the sedition charges were laid because "bringing and stamping on the cow's head... could upset Hindus".
Opponents of the proposed relocation of the 150-year-old Hindu temple said its new site would create traffic jams and noise in a Muslim-majority neighbourhood.
Local authorities in Selangor state, which surrounds the capital Kuala Lumpur, have found another site for the temple about 200 metres (yards) from the originally proposed location.
Issues related to religion, language and race are highly sensitive in Malaysia, which witnessed deadly ethnic riots in 1969.
Earlier this year Malaysia was rocked by a row over the use of the word "Allah" by non-Muslims as a translation for "God", whch saw churches and mosques firebombed across the country.