"We are not in favor of discrimination, but of course our views on the nature of marriage in our community are very well known and they won't be changing," Howard told Sky television.
Hours after the interview, the government's chief discrimination watchdog released a report that condemned 58 federal laws for discriminating against same-sex couples in the areas of financial and work-related entitlements.
Howard's center-right government amended federal law in 2004 to ensure that gay and lesbian couples cannot legally marry and to close any potential room for a legal challenge to the ban.
Gay groups accused Howard of prejudice, and also attacked his recent statements that Australia should shut its door to immigrants who are HIV-positive.
An independent human rights group, GetUp!, released a poll Thursday that showed 71 percent of Australians agreed that same-sex couples should have the same legal rights as heterosexual partners in common-law marriages, while 23 percent disagreed.
The national random telephone survey conducted by Galaxy Research on June 16-17 of 1,100 Australians over the age of 16 had a 2.7 percentage point margin of error.
"Australians don't want their gay friends and family to feel like second-class citizens," GetUp! executive director Brett Solomon said.
With elections due late this year and Howard's government trailing in opinion polls, Solomon said granting rights to same-sex couples is an "electoral necessity."
The main opposition Labor party supported the ban on gay marriage.
Howard's latest pressure over his government's treatment of homosexuals came late Thursday in an audit of federal laws and their impact on same-sex couples and their children by the Human Rights and Equal Opportunity Commission.
In its report, the commission found that 58 federal laws breached the International Covenant on Civil and Political Rights by discriminating against same-sex couples.
It recommended the laws be changed so that more than 20,000 same-sex couples gain the same financial benefits as heterosexual couples in areas such as tax, pensions, old age care, health benefits and insurance.
Howard said he would read the report but would not make any promises regarding his government's response.
"We certainly aren't a government that supports discrimination," Howard said.