Saudi Arabia's king has said Iran is putting the Gulf region in danger and has advised Tehran leaders to know "their limits".
In an interview published in Kuwait's al-Seyassah newspaper on Saturday, King Abdullah bin Abdul Aziz al-Saud said attempts by Iran to spread Shia beliefs in Sunni communities would fail.
King Abdullah said: "Saudi leaders and the Saudi state have always known their limits in dealing with nations, east and west. I explained this to Ali Larijani [Iran's nuclear negotiator] and advised him to pass it on to his government and its followers, with regard to foreign dealings."
King Abdullah also said the Israeli-Palestinian conflict should be solved by "Arabs alone".
"We don't want anyone to trade in our issues and become stronger through them," he said.
Larijani visited Riyadh this month to seek help with Washington and reassure Saudi Arabia over Iran's nuclear programme.
The US, which sees Saudi Arabia as an important ally in the region, has accused Iran of intending to make a nuclear weapon. A charge Iran denies.
The US also says Iran is "interfering" in Iraq by backing Shia military groups in the country and criticises Tehran for backing Lebanon's Hezbollah, a Shia group which is leading a move to topple Lebanon's government.
Iran is known to support Hamas, the ruling Palestinian party and a largely Sunni organisation.
Hamas has refused to recognise Israel and has been shunned by Western governments.