Chanting "information should be free" and "down with censorship," demonstrators marched through Montreal's downtown on Saturday in support of online whistleblower WikiLeaks.
About 100 people weaved their way to the U.S. consulate to protest the shutdown of the website and attempts to cut off its funding.
Organizer Nadim Kobeissi, a computer science student at Concordia University, said authorities are trying to stifle the free flow of information online.
"If the Internet is allowed to stay as it is, it will cause great political change.... where everyone has access to information equally," Mr.Kobeissi said.
"This will cause political accountability and knowledge sharing that is unprecedented."
Mr. Kobeissi, a self-proclaimed Internet freedom advocate, has created a mirror site for WikiLeaks that duplicates material no longer available on the original website.
Nearly 2,000 such sites have been created since WikiLeaks was shut down.
Bruno Joyal, a mathematics student at Concordia, said he's concerned a dangerous precedent will be set if WikiLeaks is successfully contained.
"We're approaching a situation where the United States would like to make sure that leaked secret documents cannot be published," Mr. Joyal said.
"We believe it's very important that the press be able to publish such documents."
The demonstrators also called for the release of Bradley Manning, the U.S. soldier charged with stealing sensitive and classified documents and giving them to WikiLeaks.
Similar rallies were slated to be held Saturday in the United States, Ireland and the Netherlands.
In recent weeks, WikiLeaks has released parts of a cache of more than 250,000 secret U.S. State Department diplomatic cables from around the world.
The documents, published in co-operation with several major media organizations, reveal behind-the-scenes discussions between diplomats and often unflattering assessments of foreign leaders, ranging from U.S. allies such as Germany and Italy to other nations like Libya, Iran and Afghanistan.
WikiLeaks founder Julian Assange was released on bail Thursday.
He will be confined to a supporter's mansion, but free to get back to work on his website as he fights Sweden's attempt to extradite him on allegations of rape and molestation.
Speaking Saturday outside the home in eastern England, Mr. Assange called the case in Sweden a "travesty." He also claimed he and others working for WikiLeaks face significant risks.
"There is a threat to my life, there is a threat to my staff," he said, without offering details.
"There are significant risks facing us."
U.S. Attorney General Eric Holder has said repeatedly a criminal investigation of WikiLeaks' release of the cables is under way.
- With files from The Associated Press