Diplomats from Qatar and the four states blockading the Gulf nation have exchanged heated words at an Arab League meeting in Cairo.
Tuesday's row, which erupted on live television, is the latest chapter in the three-month-old Gulf crisis in which Saudi Arabia, the United Arab Emirates (UAE), Egypt and Bahrain are blockading Qatar.
The coalition cut diplomatic and trade links with Qatar on June 5, suspending air and shipping routes to their Gulf neighbour.
The four Arab states have accused Doha of financing "terrorism". Qatar has rejected the allegation as "baseless".
The blockading states also have accused Doha of supporting regional foe Iran.
During his opening speech, Qatar's Minister of State for Foreign Affairs Sultan bin Saad al-Muraikhi referred to Iran as an "honourable country" and said ties had warmed with its neighbour since the blockade.
In response, Ahmed al-Kattan, Saudi Arabia's envoy to the Arab League, said: "Congratulations to Iran and soon, God willing, you will regret it.
"If the brethren in Qatar think they may have a benefit in their rapprochement with Iran, I'd like to say that they have this evaluation wrong in every way. The Qataris will be held responsible for such a decision." 
He added that in "the coming days will prove them wrong because we know that the Qatari people will never accept the Iranians to play a role in Qatar".