Chancellor Gordon Brown said race laws may have to be changed after British National Party leader Nick Griffin was cleared by a jury of stirring up racial hatred.
Mr Brown said most people would find some of Mr Griffin's words offensive and pledged a legislative rethink if necessary to stamp out racial hatred.
However a Home Office spokesman said Home Secretary John Reid would only "think carefully" about the need for changes to the legislation.
Mr Brown said: "Any preaching of religious or racial hatred will offend mainstream opinion in this country and I think we have got to do whatever we can to root it out, from whatever quarter it comes," he told the BBC.
"If that means that we have to look at the laws again, I think we will have to do so. Mainstream opinion in this country will be offended by some of the statements that they have heard made."
But a spokesman on behalf of Mr Reid said the Home Secretary believed defeating the "poisonous politics of race" could be done only by argument, politics and community engagement.
The spokesman said: "Parliament has only recently discussed and decided on new laws in this area. But obviously we want to make sure that legislation is effective and even-handed.
"The Home Secretary will therefore think carefully and take time to study and reflect on this judgment and its implications, including taking soundings from his ministerial colleagues.
"However, he believes that the poisonous politics of race can only ultimately be defeated by rational argument, political opposition and the engagement of the whole community in opposition to such extremism wherever it arises."
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New laws on racial and religious hatred were passed by Parliament earlier this year but were watered down following a backbench Labour rebellion.
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