Members of a number of First Nations communities sang and banged drums on the front steps of the house.
Spokeswoman Angela Acquin of the St. Marys First Nation said the legislation is harmful to the interests of Aboriginal Peoples.
"Bill C-45 is going to take away all rights of the First Nations people — the water protection, the land protection, education for our future generations," she said.
"It takes controls away from our leaders we vote in to lead our communities, to lead our people."
She said the demonstration is also their way to show support for the hunger strike of Chief Theresa Spence of northern Ontario's Attawapiskat First Nation. Spence stopped eating a week ago in an effort to get the government to show more respect for aboriginal treaties.
In a statement, Aboriginal Affairs Minister John Duncan said the government has taken steps in the last six years on priorities for First Nations, such as health, education and housing.
"While we are making progress, we too are impatient to see more change that will benefit First Nation communities," Duncan wrote.
Duncan said he has tried several times to reach Chief Spence to discuss the issue.
A number of the protesters in Fredericton entered the legislature building and were in the process of going through security before they were asked to leave.
Judie Acquin-Miksovsky said she had no intention of causing a disturbance inside the legislature and was upset that she was denied entry.
"We are people of this land," she said. "This is the house of our representatives and we have a right to those representatives to see us."
Daniel Bussieres, the legislature's sergeant-at-arms, issued a statement saying a number of individuals had attempted to move the protest inside the legislature building.
"This simply is not permissible," Bussieres says.
The protesters agreed to leave the building and the demonstration dispersed a short time later.