Even so, the survey shows Iranians continue to strongly want their country to adopt democratic institutions like free elections and a free press, the poll showed. There also remains a widespread willingness to stage unconditional negotiations with the U.S. following nearly three decades of diplomatic estrangement between the two countries.
Just 29 percent of Iranians said they have favorable views of the United States in the latest poll, which was conducted last month. In a similar survey in February 2008 - nearly a year before Barack Obama became president - 34 percent had positive opinions about the U.S.
In a further sign of wariness toward the United States, 38 percent in last month's poll said the U.S. is the greatest threat to Iran. Only Israel was ranked higher - 44 percent of Iranians said the Jewish state posed the greatest threat to their country.
Accurate public opinion polls are a rarity in Iran, whose Islamic rulers enforce strict rules of behavior and where dissidents are often imprisoned. The survey was conducted by telephone from a nearby country that the sponsors declined to identify for security reasons.
The poll was conducted for Terror Free Tomorrow, a bipartisan group that tries to undermine support for terrorism, and for the New America Foundation, a nonpartisan public policy institute. Both are based in Washington.
The latest survey was released days before Friday's national elections in Iran, in which hard-line President Mahmoud Ahmadinejad is being pressed by his main challenger, reformist Mir Hossein Mousavi.
Iran's media is largely controlled by the government, though the Iranian people increasingly have access to the Internet. That makes it hard to gauge how much information Iranians have received about Obama and his repeated statements that he is open to talks in hopes of improving relations.
"How much of Obama's message has been broadcast to them, I have no idea," said Ken Ballen, president of Terror Free Tomorrow.
The new poll shows 87 percent of Iranians favor making free elections a long-term goal for Iran, up a slight 5 percentage points from a year ago. Another 84 percent want a free press to be a long-term goal, up 6 percentage points.
Those figures were not much lower than the 90 percent who said improving the economy should be a long-term goal for Iran, where economic conditions have been poor in recent years.
Sixty percent said they favor unconditional talks with the U.S., virtually unchanged from last year.
Washington and Tehran have not had diplomatic relations since 1979, when radicals seized the U.S. embassy in Tehran and held American hostages for 444 days. They are currently at odds over Iran's nuclear program, which the U.S. says is aimed at developing nuclear weapons, a charge Iran has contested.
The survey was conducted by KA Europe SPRL, a privately owned research company.
Telephone interviews, conducted in Farsi, involved a random sample of 1,001 adult Iranians from May 11-20. The poll has a margin of sampling error of plus or minus 3.1 percentage points. The company says more than 90 percent of Iranians have landline telephones.