UPDATE 1-Rouhani says U.S. wants to cause insecurity in Iran but will not succeed

Iranian President Hassan Rouhani said on Sunday the United States wants to create insecurity in the Islamic Republic, a day after an attack on a military parade that killed 12 members of the country's elite Revolutionary Guards.

Speaking before leaving Tehran to attend the U.N. General Assembly in New York, Rouhani accused U.S.-backed Gulf Arab states of providing financial and military support for anti-government ethnic Arab groups.

"The small puppet countries in the region are backed by America, and the United States is provoking them and giving them the necessary capabilities," said Rouhani.

The attack, which killed 25 people, was one of the worst ever against the Guards and is bound to ratchet up tensions with Iran's regional rival Saudi Arabia.

"Iran's answer (to this attack) is forthcoming within the framework of law and our national interests," said Rouhani, adding that the United States will regret its "aggressiveness".