The 65-year-old Hollywood star, who has vehemently condemned the war in Iraq, made the claims during an interactive session at the Tribeca Film Festival - an 11-day event in New York, reported Ace Showbiz.
One audience member asked whether Sarandon, who was answering questions alongside documentary filmmaker Michael Moore, believed she was under surveillance by the government.
Sarandon said, "We know we're under surveillance. I've had my phone tapped. I was denied a security clearance to go to the White House and I don't know why. Do you know why?"
The "Stepmom" star said she knew she was being watched by the government as she had twice seen a file held on her through Freedom of Information requests.
Moore, who directed "Fahrenheit 9/11" and "Capitalism: A Love Story", said, "I never think about it. It would unwind me. I assume everything I'm saying in an email or saying on the telephone is being looked at."
Sarandon has been actively involved in promoting liberal political causes and supporting human rights, donating money and lending her voice to campaigns since the 1980s.
During presidential elections, she has thrown her support behind Democratic and independent candidates. Sarandon has taken part in protests against the 2003 invasion of Iraq and in support of withdrawing troops.
She has addressed protesters in the Occupy Wall Street movement, encouraging them to fight harder to hold the government accountable.
