Iran summoned Bahrain's ambassador in Tehran after his foreign minister told the Islamic republic to stop interfering in his nation's internal affairs, state media reported on Friday.

Foreign Minister Sheikh Khaled bin Ahmed al-Khalifa on Thursday warned Iran to stop meddling over a proposal for Bahrain to form a union with Saudi Arabia.

Al-Qaida chief Ayman al-Zawahiri urged Saudis to follow Tunisians, Egyptians and Libyans in rising up against their rulers, U.S.-based monitors said Thursday.

"Why don't you rise while you are the sons of the proud and strong tribes that look down upon death in order to lift the humiliation and the oppression?" Zawahiri asked in a video translated by the SITE Intelligence Group.

Bahrain on Thursday warned Iran to stop interfering in its internal affairs while affirming its support for a union between the six nations of the Gulf Cooperation Council.

Foreign Minister Sheikh Khaled bin Ahmed Al-Khalifa made the remarks a day after Iran called on its people to protest on Friday against the union that Gulf officials say will start with Bahrain and Saudi Arabia.

Iran has called on its people to stage rallies after this week's Friday prayers to protest against what it described as a U.S. plan to annex Bahrain to Saudi Arabia.

The Islamic Propagation Coordination Council, which organizes state-backed protests, urged Iranians "to protest against the American plan to annex Bahrain to Saudi Arabia and express their anger against the lackey regimes of Al-Khalifa and Al-Saud."

The United States and 18 other countries have started in Jordan what was described as the largest military exercises in the Middle East in 10 years, focusing on "irregular warfare," top officers said on Tuesday.

"Yesterday we began to apply the skills that we have developed over the last weeks in an irregular warfare scenario ... They will last for approximately the coming two weeks," Major General Ken Tovo, head of the U.S. Special Operations Forces, told reporters in Amman.

Gulf leaders agreed Monday to allow more time for further discussions over a Saudi proposal to turn the six-nation council into a union likely to start with the kingdom and unrest-hit Bahrain.

The leaders who met in Riyadh have instructed their foreign ministers to "continue studying the report of the special commission," said Saudi Foreign Minister Prince Saud al-Faisal.

Iranian MPs on Monday condemned a planned union between Saudi Arabia and fellow Sunni-ruled Bahrain, news agencies reported.

"Bahraini and Saudi rulers must understand that this unwise decision will only strengthen the Bahraini people's resolve against the forces of occupation," they said in a letter, referring to Saudi military support for Manama.

Liberal civil society groups in Gulf States called Monday on Saudi and Bahraini leaders to postpone plans to announce a union between them, saying such a step must be preceded by a referendum.

"We urge the Saudi and Bahraini leaderships to review such a step and calculate the reactions of the two peoples," the Gulf Forum for Civil Societies said in a statement signed by its secretary general Anwar al-Rasheed.

Oil fell in Asian trade Monday amid mounting worries over Europe's debt crisis and calls by major crude producer Saudi Arabia for prices to fall further, analysts said.

New York's main contract West Texas Intermediate crude for delivery in June was down 84 cents to $95.29 per barrel while Brent North Sea crude for June shed 41 cents to $111.85 in morning trade.

Gulf leaders at a meeting in Riyadh on Monday will discuss a Saudi proposal to develop their six-nation council into a union, likely to start with the kingdom and unrest-hit Bahrain, officials said.

The Gulf Cooperation Council leaders "will discuss a form of union between Saudi Arabia and Bahrain," said a top Gulf official, requesting anonymity.