Speaking to Al Jazeera, Syed Hamid Albar said the government was "very reluctant to use the ISA" which he said was only implemented when the government felt the security and safety of the country was at stake.
"We are very a sensitive country where we are multiracial, multicultural, multireligious, and if you start to incite people it can go out of hand," he said.
"So I think ultimately this is the best thing to do, to allay the fear of the public."
Earlier in a press briefing Syed Hamid defended the use of the ISA, saying other countries had similar laws, and was "no different from the Patriot Act" passed in the US following the September 11 attacks.
Syed Hamid's comments came after the US state department on Thursday demanded "full protections under Malaysian law" for the detained protest leaders.
Sean McCormack, a department spokesman, urged the government to treat the five men fairly and provide due process in a speedy and transparent manner.
"It is our firm position that those individuals who want to peacefully express themselves in a political forum or any other forum should be allowed to do so," he said.
Malaysian authorities have sent the five men to the Kamunting detention camp for ISA detainees, in the northern state of Perak.
Police have said the men could be held for up to two years - a term extendable at the discretion of the government.
Abdullah Ahmad Badawi, the Malaysian prime minister, justified the arrests saying the group was organising events that were "undesirable to national security and public safety".
"I am duty-bound to act because the people want the government to take action," he said late on Thursday.
"The people don't want to see this country in chaos."
Critics, however, have condemened the use of the ISA - not implemented for six years - as a misuse of the law.
"It was designed for the communist insurgency and threat, that was 40 years ago," Dr Azmi Sharom, an associate law professor at the University of Malaya told Al Jazeera.
"That has been passed, that has gone. So now it is being used for political purposes. The ISA is definitely something that should be done away with."
Despite the arrests, P Waytha Moorthy, one of Hindraf's founding members, said the group would continue its protests saying he would continue to lead the campaign from his current base in London.
Hindraf leaders say protests will continue [AFP]
He urged supporters to remain calm and avoid violent tactics, but warned that people could resort to other means to get their message across if they lose confidence in the system.
"The government has made us heroes of the community," he told the Associated Press.
"They can take all of us in, put us behind bars, but they have not solved the issue."
Waytha Moorthy, whose brother is among the five held under the ISA, said the government was deliberately making Hindraf look like a threat in order to "silence the voice of the minority".
"On our part, we are committed to a peaceful struggle," he said. "I'm still hopeful that the government will engage in dialogue with us."
Waytha Moorthy is currently lobbying foreign governments and human rights groups to call for the release of the five men.
The government maintains that it does not discriminate against ethnic Indians but Hindraf insists that an affirmative action programme granting privileges to ethnic Malays in business, jobs and education is tantamount to unfair treatment.