"We are having productive discussions with the Islamic Republic of Iran," Trump wrote in a post on Truth Social.
He said the US blockade of Iranian ports remains in effect and that oil is flowing through the Strait of Hormuz.
"We will not be attacking Iran at any time prior to the Midterm Elections to be held in the United States on November 3rd," Trump said.
The United States and Israel launched strikes on Iran in February and the war - and its $US3 billion ($A4.3 billion) monthly price tag - has become a key issue on the US campaign trail.
Trump has repeatedly said he expected oil prices to drop sharply after the elections but high petrol prices and the Iran war are weighing heavily on Republican candidates and threatening their congressional majority.
Iran and the US have exchanged proposals in recent weeks aimed at ending the war and reopening the Strait of Hormuz, a vital global energy shipping route.
Trump, while stumping for Republicans this week, has hinted that he was confident that an endgame to the war cold come in the days before or after the election while also suggesting that he remained open to resuming full-scale military operations against Iran.
Negotiations had appeared at a standstill since Trump late last month publicly rejected an Iranian proposal to reopen the Strait of Hormuz within seven days if the US met certain conditions.
Iran, however, said last week they had received a US counterproposal.
And Foreign Minister Abbas Araqchi on Thursday said he expected Iran would offer a formal reply within days.
"The diplomatic process is still continuing," Araqchi said.
with AP
