Global benchmark Brent crude was up 3.3% at $97.90 (£73.11), while US-traded West Texas Intermediate was 3.2% higher at $97.55.
Oil prices remain far higher than they were before the war started on 28 February.
The ceasefire was announced on Tuesday evening Washington time shortly before a 20:00 EDT (00:00 GMT on Wednesday) deadline set by US President Donald Trump.
He had warned that “a whole civilisation will die tonight” if no deal was reached.
One of the conditions of the agreement was that ships would be able to safely use the Strait of Hormuz.
Ships in the Gulf have received a warning from Iran’s navy that any vessels seeking to cross the Strait of Hormuz without permission “will be targeted and destroyed”, the shipping brokerage firm SSY has confirmed to BBC Verify.
Only a handful of ships have crossed the waterway since the deal was announced – well below the rate of some 130 vessels that transited daily before the war.
It will take a minimum of 10 days to clear the existing backlog of vessels, even if the strait resumes its usual volume of shipping, according to maritime tracking firm Pole Star Global.
There is also disagreement over whether Lebanon is included in the ceasefire.
On Wednesday, Israel launched its heaviest bombardment of the country in this conflict, killing at least 182 people.
Hezbollah said in a statement posted on social media that it had fired rockets at northern Israel. The Iran-backed militia says it was in response to ceasefire violations.
US Vice President JD Vance is scheduled to take part in negotiations with Iran in Pakistan on Saturday.