Iranians began national celebrations Thursday to commemorate the anniversary of the 1979 revolution that ousted a pro-Western monarchy and brought Islamists to power.
State television aired footage of rallies in Tehran and other cities and towns across the country, many of them in frigid winter weather conditions.
In the capital, hundreds of thousands converged on historic Azadi (Freedom) Square, where President Hassan Rouhani made a speech addressing Iran's political camps.
"True [conservatives], true reformists and true moderates are all revolutionary," he said in remarks broadcast live on state television. "In our time, 'revolutionary' means being in favor of participation, tolerance, and resistance, and having goods capable of competition in world markets."
The anniversary of Iran's 1979 revolution comes two weeks ahead of crucial parliamentary elections, when the moderate Rouhani will hope for a shift in the balance of power in parliament, which is currently dominated by conservatives.
Demonstrators chanted traditional slogans against the U.S. and Israel, and the streets in many cities were decorated with anti-U.S. and anti-Israeli banners and posters.
Many Iranian leaders came to the rallies, including Qassem Soleimani, chief of the Quds Forces of the elite Revolutionary Guard, who made a brief appearance.
Young people at one demonstration reconstructed a scene from mid-January that saw U.S. Navy sailors detained by Iranian Revolutionary Guards.
State television has repeatedly broadcast pictures of the 10 captive sailors with their hands on their heads. On Wednesday night, a brief video also showed one soldier in tears.