There is no justification for Umno Youth to "run amok" no matter how insensitive an article, greeting or image is deemed to be, said MCA's Religious Harmony Bureau, in response to the Malay party wing's defence of its rally in front of DAP headquarters Tuesday.

"There are laws and penalties to handle any offences against race and religion. Quoting religious or racial sensitivities as a justification to commit another is a greater wrong both morally and legally.

"It is not a defence and does not render any groups or individuals any self-appointed to retaliate beyond the parameters of the law.

"Sanctioning mob-rule only encourages further violence on individuals or destruction of buildings at any time," its chairperson Ti Lian Ker said in a statement.

Umno Youth defended their right to demonstrate to protect the dignity of Islam from supposedly being insulted by a Facebook posting allegedly by DAP lawmaker Nga Kor Ming.

But Ti said they could always fall back on old favourites such as lodging police reports, or take legal action against Nga if he committed any wrong.

"There are avenues to raise a complaint like lodging a police report for sedition, or, as Nga is a lawyer, to petition for a resolution at the Bar Council annual general meeting to sanction him for the offensive cartoon.

"Nobody may resort to vigilantism and take the law into one’s own hands," said the MCA leader.

He added that he was "disturbed" some leaders actually condoned and justifed the heated march.

"Leaders should stop justifying these reactions or overreactions giving these potential mobs any semblance or a legal moral right to 'run amok' at any issue they deem is a slightest provocation," Ti said.

On Tuesday, a group of Umno Youth marched to the DAP headquarters in Pudu to demand an apology from Nga over alleged social media postings purportedly by him which they claim to be insulting to Islam.

Nga is alleged to have posted a Hari Raya Aidilfitri greeting featuring the American flag and a cartoon of children in baju melayu asking for donations or 'dedak' (animal feed) instead of 'duit raya'.

'Dedak' in political circles refers to political handout to appease or win over supporters.

The American flag posting was posted on a Nga Kor Ming Facebook fanpage that Nga claims is unauthorised.

The cartoon was reportedly published on the same page but Malaysiakini cannot independently verify this as the fanpage has been deactivated.

Nga denies making the postings, and lodged a police report over the matter.

Umno supreme council member Ismail Sabri Yaacob and Cheras division chief Syed Ali Alhabshee said the protest was justified as the postings were insulting, but Culture and Tourism Minister Nazri Abdul Aziz said it is wrong to throw hell notes.