An Iranian man marches with a portrait of the country's Supreme Leader Ali Khamenei (L) alongside a woman holding up another of Islamic Revolution founder Ayatollah Ruhollah Khomeini (R) during a ceremony celebrating the 40th anniversary of Islamic Revolution in the capital Tehran on February 11, 2019.
State TV showed crowds defying cold rainy weather and carrying Iranian flags while shouting "Death to Israel, Death to America", trademark chants of the revolution.
On February 11, 1979, Iran's army declared its neutrality, paving the way for the fall of US-backed Shah Mohammad Reza Pahlavi.
In his address on Tehran's Azadi Square, Rohani said the "enemy will never reach its evil objectives", vowing that Iran will defeat USA sanctions.
He said that while Iran will continue to have "constructive engagement" with the global community, it will not ask for permission to produce any type of missile it wants.
Iran displayed its ballistic missile capabilities during a parade marking the anniversary, including the Zolfaqar, a ground-to-ground missile with a 700 kilometre (435 mile) range and the Qiam, with a range of 800 km, according to Tasnim news agency.
In January, Mr Rouhani said Iran was facing its worst economic crisis since the Shah was toppled.
The large turnout in state-sponsored rallies came as Iranians face mounting economic hardships.
No-deal Brexit 'could cost 600,000 jobs worldwide'
But he confirmed a meaningful vote on whether to accept or reject a revised deal might not happen until March. British lawmakers in January overwhelmingly rejected the deal she had agreed with Brussels previous year .
U.S. President Donald Trump pulled out of Iran's 2015 nuclear deal with world powers a year ago and re-imposed sanctions on Tehran, dealing a blow to the country's economy.
Despite Iran's efforts to hide the facility, Israel has nevertheless discovered, tracked and uncovered it, the network said, as part of its effort to thwart Iran's military entrenchment in Syria.
Dismissing calls that Iranian regional influence should be curbed, the deputy commander of Iran's Islamic Revolutionary Guards Corps (IRGC) was quoted as saying on February 11 that "the enemy can not ask us to leave the region".
TEHRAN: Iran´s president on Monday insisted "enemy" plots against the country would fail as vast crowds marked 40 years since the Islamic revolution at a time of heightened tensions with the United States.
Regional power Saudi Arabia and other Arab countries have viewed Iran with great suspicion since the Islamic Revolution swept the Shah from power, fearing Khomeini would inspire Islamic militants across the region.
"The presence of people in this celebration means that plots by the enemies ... have been defused", Rouhani said.
State television offered blanket coverage of the commemorations, showing marches in cities ranging from Abadan in southwestern Iran to Mashhad in the northeast.
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