Iran's new president has called on the West to abandon the "language of sanctions" in dealing with his country over its contentious nuclear programme, hoping to ease the economic pressures now grinding its people.
He also expressed his country's support to Syria's embattled leader Bashar Assad's regime, saying no force in the world will be able to shake their alliance.
President Hasan Rouhani spoke after being sworn in as president in an open session of parliament, capping a weekend that saw him endorsed by Ayatollah Ali Khamenei, Iran's supreme leader.
Mr Rouhani, a moderate cleric who won a landslide victory in the June 14 presidential elections, continued his call for dialogue with the West while asking foreign powers to respect Iran in its negotiations.
"If you seek a suitable answer, speak to Iran through the language of respect, not through the language of sanctions," the president said in a speech broadcast live by Iranian state television. He later added that any negotiations would require "bilateral trust building, mutual respect and the lessening of hostilities."
Iran is under United Nations sanctions as well as unilateral Western oil and banking sanctions over its refusal to halt uranium enrichment, a technology that can be used to power reactors producing electricity or build nuclear weapons.
Iran says its nuclear programme is peaceful and geared towards generating electricity and producing radioisotopes to treat cancer patients.
Mr Rouhani replaces President Mahmoud Ahmadinejad, who struck a hard-line approach when dealing with the West and its sanctions over the nuclear program. The sanctions have hit the country's vital oil exports and blocked transactions on international banking networks. Inflation is running at more than 35 percent. The Iranian rial has lost more than two-thirds of its value against the U.S. dollar since late 2011.
Many Iranians and foreign diplomats hope that Mr Rouhani, a former top nuclear negotiator, can strike a more conciliatory tone in negotiations. Those hopes could be seen by the attendance at his swearing in, as the audience included leaders and other representatives from more than 50 countries. It was the first time since Iran's 1979 Islamic Revolution that foreign dignitaries attended the swearing-in ceremony of an Iranian president.
In Washington, White House spokesman Jay Carney said Mr Rouhani's inauguration represented "an opportunity for Iran to act quickly to resolve the international community's deep concerns over Iran's nuclear program."
"Should this new government choose to engage substantively and seriously to meet its international obligations and find a peaceful solution to this issue, it will find a willing partner in the United States," Mr Carney said in a statement.
During his speech, Mr Rouhani said Iran opposes "any change in political systems through foreign intervention." Iran is a close ally of Syrian President Bashar Assad, whose country remains in the grips of a bloody two-year civil war. Assad's government has received fighters from the Iranian-backed Hezbollah, helping government forces gain ground in recent weeks.
"Peace and stability in all neighboring regions is a need and necessity for Iran," Mr Rouhani said.
Syria's state-run news agency SANA reported that Mr Rouhani told Syria's prime minister that no force in the world would shake the alliance between the two countries. Syria has been Tehran's strongest ally in the Arab world since Iran's 1979 Islamic Revolution.
Mr Rouhani also said that Iran is "not after changing borders and governments." He did not elaborate, but it appeared to be a reference to Israel, which other Iranian leaders have demanded be destroyed in the past.