Mediators have achieved progress in efforts to get the United States and Iran back to negotiations and avert an all-out war in the Middle East, two regional officials said Monday, with a pause in attacks coming after a period of rapidly escalating tensions.

The comments came after neither the U.S. nor Iran reported carrying out any attacks for three straight days — a respite after about two weeks of sustained bombardments that had led to increasing fears of a return to all-out war.

Iran's foreign ministry on Monday said it was not currently involved in negotiations with the United States, despite a halt in recent fighting between the two sides.

"At present, we are not engaged in any negotiations with the United States," said the ministry's spokesman Esmaeil Baqaei at a weekly press briefing, denying reports that Iran had requested talks.

Iran's foreign ministry on Monday said the United States was not involved in recent talks with Oman over the administration of the strategic Strait of Hormuz.

"These talks have no connection with the United States. They are a bilateral matter between Iran and Oman, and they are continuing," said the ministry's spokesman Esmaeil Baqaei in a weekly press briefing, adding that the waterway "remains closed".

Iran's foreign ministry said on Monday it had summoned the French ambassador to Tehran to protest what it described as "interference in Iran's internal affairs" by two diplomats who were briefly detained earlier this month.

"Yesterday, the French ambassador in Tehran was summoned to the Ministry of Foreign Affairs, where it was stressed that the French government must cease such actions and such interference in Iran's internal affairs under misleading labels," said the ministry's spokesman Esmaeil Baqaei in a weekly press briefing, adding that the diplomats had carried out activities "that were in no way justified".

Iran's foreign ministry warned on Monday of "unforeseen" consequences following Ukraine's attack on an Iranian vessel in the Caspian Sea over the weekend.

"This action by Ukraine was an absolutely illegal and unjustified act, contrary to the Charter of the United Nations, as well as a dangerous act of adventurism that will certainly not go unanswered by us," the ministry's spokesman Esmaeil Baqaei said in a weekly press briefing, adding that the consequences of Ukraine's action "will certainly be unforeseen".

Syrian state media said Israeli forces carried out an incursion into the country's south on Sunday, a day after the visiting U.N. chief urged an end to Israeli violations and respect for Syria's sovereignty.

State news agency SANA said that "Israeli occupation forces carried out an incursion early Sunday into the villages of Maariya and Al-Aarda in the Yarmuk basin in the west of Daraa province".

Palestinian officials said Israeli settlers set fire to two mosques in the occupied West Bank overnight Sunday, after this week's deadly clashes in the territory left six people dead.

Iran passed another night without U.S. airstrikes on Sunday, as Washington paused a war nearing its fifth month and reports emerged that concerns over dwindling munitions were restraining plans for further escalation.

The lull has revived hopes of a return to negotiations after nearly two weeks of consecutive nightly U.S. bombardments, although U.S. media reported the pause could also reflect pressure on stockpiles of Patriot interceptors and other defensive weapons.

Israeli Prime Minister Benjamin Netanyahu will meet US President Donald Trump at the White House on Tuesday, the Israeli leader's office said.

Palestinians in the occupied West Bank village of Tell on Saturday buried four men killed during a clash with Israeli settlers in the village the previous day, local officials said.