"I appeal to all, all authorities in Myanmar, civilian authorities and military authorities, to indeed put an end to this violence that, in my opinion, is creating a situation that can destabilise the region," he told the media in New York on Tuesday.
In a rare move, the UN chief has also written to the Security Council expressing his concern that the violence could spiral into a "humanitarian catastrophe with implications for peace and security that could continue to expand beyond Myanmar's borders."
“I have condemned the recent attacks by the Arakan Rohingya Salvation Army. But now we are receiving constant reports of violence by Myanmar's security forces, including indiscriminate attacks,” said Guterres.
Hundreds of thousands of Rohingyas have fled the northwestern Rakhine state since violence broke out on Aug 25, when insurgents attacked 30 police camps and an army base.
The ensuing clashes and a military counter-offensive have killed at least 400 people.
The UN Security Council met behind closed doors last week to be briefed on the situation at the request of Britain, Reuters reported.
"If it continues to deteriorate then one of the things that we can do is to hold further meetings to shine a spotlight on the situation there," Britain's UN Ambassador Matthew Rycroft said on Monday.