Iran and the US remain entrenched in their positions over the standoff in the Strait of Hormuz, a dispute that could derail Pakistan's efforts to broker lasting peace between the two adversaries.

Iranian leaders are refusing to re-open the strategic waterway to international shipping as long as the Trump administration maintains its blockade on Iranian ports, The Caspian Post reports, citing foreign media.

The US has ruled out any easing of the blockade and further ratcheted up tensions this week by seizing several Iranian tankers in the Indian Ocean.

"Reopening the Strait of Hormuz is not possible amid a blatant violation of the ceasefire," said Iranian parliament speaker Mohammad Bagher Ghalibaf - who led Tehran's delegation in the first round of talks in Islamabad.

The country's president, Masoud Pezeshkian, said Tehran is willing to return to talks but said the US "breach of commitments, blockade and threats are main obstacles to genuine negotiations".

Pakistan has raced to set up fresh negotiations after a first round of talks in Islamabad earlier this month failed to break the deadlock. A return to full-scale war was narrowly averted earlier this week after Trump unilaterally announced an extension of the ceasefire just hours before its expiry.

Oil prices jumped four percent before falling back on Thursday, as new negotiations remained a distant prospect.