Bahrain summoned Iran's acting charge d'affaires Sunday to protest against its supreme leader voicing support for "oppressed people" across the Middle East including in Bahrain, state media said.

The foreign ministry handed "an official protest memorandum" to Mortaza Sanubari over "statements made by Ali Khamenei against the kingdom of Bahrain," BNA news agency said.

The U.S. State Department on Sunday officially transferred to American lawmakers the complex text of an Iran nuclear deal, firing the starting gun on what is set to be a bitter Congress battle.

Top U.S. administration officials are girding for a huge fight with the Republican-controlled Congress, which, while it cannot modify the terms of the historic deal, can vote to approve or disapprove the accord.

A senior Hizbullah official announced Sunday that the nuclear deal that was recently reached between Iran and the top world powers will not push the Tehran-backed party to change its policies.

“Hizbullah will remain the same after the Iranian nuclear agreement. Today, tomorrow and everyday it will be the party of resistance that supports Palestine and protects Lebanon from every threat, be it Israeli or takfiri,” Sheikh Nabil Qaouq, the deputy head of the party's Executive Council, declared.

German Economy Minister Sigmar Gabriel flew to Iran Sunday, becoming the first top Western official to visit the country since world powers and Tehran reached a historic nuclear deal.

Gabriel, who is also Chancellor Angela Merkel's deputy and energy minister, embarked on the three-day trip with a "small delegation of representatives from companies, industry groups and the sciences", his ministry said in a statement.

The return of oil from Iran following the landmark nuclear energy deal with world powers could create fresh tensions within OPEC but may reinforce the cartel's output strategy, analysts say.

Tehran and major powers -- Britain, China, France, Germany, Russia and the United States -- clinched a historic agreement in Vienna on Tuesday aimed at ensuring Iran does not obtain a nuclear bomb, and which paves the way for the removal of sanctions and the gradual return of Iranian oil to the global market next year.

The landmark deal on Iran's nuclear program that Russia helped steer through marathon talks is a diplomatic fillip for Moscow which will boost trade with Tehran but could also hit much-needed energy revenues, analysts said.

Iran and the P5+1 group -- Russia, the United States, China, Britain, France and Germany -- struck an agreement on Tuesday that would progressively lift economic sanctions against Tehran in exchange for limitations on its nuclear program.

U.S. Defense Secretary Ashton Carter heads next week to Israel and Saudi Arabia -- a diplomatic charm offensives to two countries that have expressed serious concerns over the Iran nuclear deal.

Carter, who will also visit Jordan, will be renewing US security commitments in the region, some of which serve as a buffer to Iran's "destabilizing behavior," a senior Pentagon official said Friday.

Iran's supreme leader Ayatollah Ali Khamenei said Saturday that a landmark nuclear deal with world powers would not affect the country's avowed stance against an "arrogant" United States government.

The remarks were greeted by chants of "Death to America" from the crowd at a ceremony in Tehran to mark the end of the Muslim fasting month of Ramadan.

Iran's nuclear deal with major powers will boost "security, stability and regional cooperation," President Hassan Rouhani told Oman's Sultan Qaboos, state news agency IRNA reported Friday.

"Contrary to the opinion of some in the region, this agreement will actually reinforce security, stability and cooperation between neighbors," Rouhani told the Omani leader in a telephone call.

U.S. Secretary of State John Kerry Friday fought back against criticism of a hard-won nuclear deal with Iran, insisting U.N. inspectors will have plenty of time to detect any Iranian bid to cheat.

Under the terms of the deal struck Tuesday in Vienna after almost two years of negotiations, Iran has agreed to give the U.N. nuclear watchdog access to suspect sites, including military bases, as the world seeks to stop the Islamic republic developing atomic arms.