"I accepted acting against national security through having contacts with foreigners, but I did not do it intentionally and knowingly," Ramin Jahanbegloo told the Iranian state news agency INSA after his release on Wednesday.
"During my prison term I sensed that American organisations put me in a position that I myself did not want to be in," said Jahanbegloo, formerly a prominent thinker and writer on democracy and non-violence.
"I used to write articles on some sites which were run by [US] security officials, and did so unknowingly." he said, apparently referring to his articles on opendemocracy.net.
Several Iranian dissidents have in the past made apparent confessions to the media during or after their detention.
The European Union has criticised Jahanbegloo's treatment and western diplomats said his detention was aimed at intimidating and silencing critics of Tehran.
Opendemocracy.net have rejected all suggestions that they are run by US security officials, stating they are independent and do not receive support from any governments.
Iranian democracy activists have asked the US not to help them
Jahanbegloo also publicly rejected his former belief that it was possible for Iranians to peacefully rise up and replace their theocratic government with a democratic system.
"I think that a velvet revolution cannot be carried out in Iran, since the situation in Eastern Europe is not comparable to that of Iran," he said.
Arrest and imprisonment
Jahanbegloo, who also holds Canadian nationality, was arrested on charges of having ties with foreigners as he tried to leave Iran on April 25.
During his four-months in prison, his supporters said he was kept in solitary confinement in a single room where the light was always on.
In addition, in May, soon after his arrest, Jahanbegloo was seen at least twice in the medical clinic at Tehran's Evin prison where political prisoners are usually held.
"It's a bad sign because it may mean he's been tortured," Houchang Chehabi, a close friend and professor at Boston University, told The Ottowa Citizen.
In June 2003 another Canadian-Iranian, photojournalist Zahra Kazemi, died in prison in Iran after she was arrested while photographing Evin prison.
Zahra Kazemi died in an Iranian prison
Her family and doctors who examined her body said she had been tortured, beaten and raped. She died from a fractured skull.
The Iranian government said that Jahanbegloo was arrested for taking part in a US effort to instigate a "velvet revolution" in Iran, a reference to the peaceful overthrow of Communist rule in Czechoslovakia in 1989.
"His case is a security-related one," Jamal Karimi-Rad, the Iranian justice minister, said.
His calls for democracy
Before his imprisonment Jahanbegloo was one of the most prominent of a group of Iranian dissidents, intellectuals and academics calling for a peaceful reform of the Iranian government.
"Democracy and non-violence ... are inseparable," he wrote on his website.
"Where democracy is practiced, people are honored for what they are. This requires transformation of human relations until none are violated because all participate in the democratic power."
Iranian students are often the loudest advocates of reform
"To have power in a democracy means to take part in the decision-making that affects each one's fate. It means self-institution and self-rule."
Jahanbegloo said that the 1979 Iranian revolution had been founded on the right ideals but had lost its way. He argued that the duty of Muslims was to try to find a new way to combine Islam, democracy and a respect for human rights.
"Today Iran is going through a cycle of erratic oscillations in which moments of democratic hope alternate with times of great despair."
"Today the true challenge for the Muslim community against religious obscurantism is to help advance the agenda of democratic change and modernization inside the Islamic world."
Jahanbegloo, a former University of Toronto lecturer, was never formally charged during his time in prison.
The Iranian government has not said if he would be free to travel abroad.