Christine Assange said she would take protests in support of the founder of WikiLeaks to Parliament House next Thursday, where Obama is due to address a special sitting of lawmakers under extremely tight security.
"I'll get as close as I can," she said.
Assange's anti-secrecy website has enraged governments around the world by dumping hundreds of thousands of confidential US diplomatic cables on the Internet.
His mother fears he will be rendered to the United States after recently losing a fight against his extradition from Britain to Sweden, where he is wanted for questioning on allegations of rape and sexual assault.
"I'm asking Australians around the country on November 17th to refuse to celebrate the Obama visit, and instead replace it with a day of support for Julian," she told the AAP news agency.
"Both political parties have been spineless in standing up to the US over this," Assange's mother added of the Australian government's response to his case.
"Whatever the US wants, the Gillard government is handing it over. And the opposition isn't much better."
Australia has been providing Assange with consular support and though it has made its "expectation of due process" clear to Britain and Sweden, the foreign ministry has warned it "cannot directly intervene in legal processes of other countries."
Obama's visit will be the first by a US president since former leader George W Bush was in Australia for the Asia Pacific Economic Cooperation (APEC) forum in 2007.
Obama had to cancel two previous trips Down Under, once because of the Gulf of Mexico oil spill and the other to oversee passage of domestic health reforms.
The president's visit on November 16 and 17 will mark the 60th anniversary of the military alliance between Australia and the United States and stress an increasing US diplomatic and military focus on the Pacific region.
Obama will travel to the Indonesian resort island of Bali afterwards for the East Asia summit.
Last Updated (Thursday, 10 November 2011 11:07)