US President Barack Obama has pledged to stand by his Gulf allies with military force if necessary, amid heightened tensions with Iran.

He reassured Arab leaders, after a two-day summit, that the US was committed to protecting them in a time of "extraordinary changes", the BBC reported.

Speaking at Camp David near Washington, Obama said a nuclear deal with Iran was not a threat to Gulf nations.

A joint statement pledged new co-operation in many areas.

These included counterterrorism, maritime security, cyber-security and ballistic missile defence.

The six-nation Gulf Co-operation Council (GCC) is made up of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and UAE.

"I was very explicit ... that the United States will stand by our GCC partners against external attack,'' Obama pledged at the end of the talks.

The president said he hoped that working together would help achieve "the kind of peace and good neighborliness with Iran" that the nations present sought.

The joint statement said that in the face of any aggression, the US would stand with the Arab nations "to determine urgently what action may be appropriate, using the means at our collective disposal, including the potential use of military force, for the defense of our GCC partners".