Trump has emerged as the front-runner to the alarm of many Americans who oppose the billionaire's controversial comments on racism, foreign policy and immigration. He is poised to clash with Democratic front-runner Hillary Clinton in November.
"Most Americans do not agree with Donald Trump's racist, anti-women, anti-LGBT practice. We are not that country. Hopefully, that will prove itself," Penn, 39, said during an event here.
Penn, who campaigned extensively for President Barack Obama during the 2008 elections and served as Associate Director in the White House Office of Public Engagement, said there are many who still did not vote for Trump despite him emerging as a front-runner.
Penn said he did not have a lot of work as there was a strike by Hollywood scriptwriters in 2007-08 so he decided to go to Iowa for a weekend trip but ended up spending more than two months.
The actor said it was not "weird" to work in the Obama administration as "it is an honour to serve your country".
Penn took his role seriously as he was worried about messing up things and being criticised in the papers.