President Donald Trump on Friday said that the US had agreed to continue talks with Iran but that he still considered the ceasefire to be over, signalling that military operations could continue.
In a post on Truth Social, Mr Trump said Iran had requested further negotiations.
"The Islamic Republic of Iran has asked us to continue 'talks'," he wrote. "We have agreed to do so, but the United States has stated to them, in no uncertain terms, that the ceasefire is over!"
He first declared the end of the ceasefire on Wednesday, a day after the US resumed strikes on Iran, igniting fears of a return to full-blown war.
Regional mediators, including Qatar and Pakistan, scrambled on Friday to prevent the conflict from escalating further.
The US strikes came in response to attacks, blamed on Iran, on commercial shipping in the Strait of Hormuz.
Iran responded by launching missiles and drones at US military facilities in Kuwait, Bahrain, Jordan and Qatar.
As of Friday, an uneasy calm had settled, as mediators pushed for a return to diplomacy.
Speaking at the Nato summit in Ankara, Mr Trump suggested that negotiations with Iran may continue, but expressed little confidence they will succeed and referred to Iran's leaders as "scum".
"They can talk, but I think they're wasting their time. They're a bunch of lying guys," he said.
Negotiations now appear to be deadlocked over the Strait of Hormuz.
While the US aims for the war were initially focused on dismantling Iran's nuclear programme, degrading its missile capabilities and bringing about the fall of the regime, negotiations have more recently shifted to securing the reopening of the vital waterway.
