The 30-second spot will run on several cable channels in the San Francisco area, the campaign said.
Barr, who became famous playing a blue-collar wife on the hit sitcom "Roseanne" in the 1980s, became the candidate of the Peace and Freedom Party after being rejected by the Green Party. Her runningmate is Cindy Sheehan, who became an anti-war activist after her son was killed in Iraq in 2004.
The commercial tells voters they are "American," not Republicans or Democrats.
It continues: "Don't vote your fear ... vote your conscience. Choosing the lesser of two evils is still choosing evil."