Waving placards imploring Obama to "support us, the people," protesters called for the June 12 elections -- which the government claims was won by the incumbent president Mahmoud Ahmadinejad -- to be annulled.
Many protestors wore green, a color that has become symbolic of the campaign of Mir Hossein Mousavi, the opposition leader who claims he won the vote.
"Everybody (in Iran) is tired," said a protester named Zohra who was in a crowd of hundreds demonstrating outside the White House. "They want freedom of speech, to pick up their own president."
Another demonstrator, Babek Talebi praised Obama's public handling of the crisis, which has seen the United States condemn violence against protestors, while trying to avoid the appearance of meddling in Iranian affairs.
"We are quite happy with the way the Obama administration has handled this issue until now," said Talebi.
"But we don't want US politicians to make a political football with Iran," he said.
"Iran has changed for good, it's not going to be the same."
Similar demonstrations took place in Los Angeles and New York.
-----------------------------------------------------------------------------------------------------