Iran's Foreign Ministry on Monday expressed its "readiness to participate" in U.S. President Donald Trump's proposed Gaza Strip ceasefire deal, as negotiators gathered in Egypt for talks on its possible implementation.

Iran, which in June was attacked by both Israel and the U.S. in an intense 12-day conflict, has "hope for the immediate delivery of humanitarian aid to the oppressed people of Gaza," the statement posted to the ministry's official X account said.

Tehran said there was a "legal and moral responsibility of all governments to support the legitimate and lawful struggle of the Palestinian people to realize their right to self-determination and liberation from the yoke of occupation, apartheid and colonialism" by Israel.

Any end to the war "does not negate the responsibility of governments and competent international institutions to pursue legal and judicial action" against Israel, the statement said, "nor the identification and prosecution of those who ordered and carried out war crimes, genocide, and crimes against humanity in the Gaza Strip."

The ministry also said there are "dangerous dimensions and aspects of this proposal," warning of what it called "repeated breaches and obstructionism" by Israel in past ceasefire efforts.

U.S. President Donald Trump said in a post to social media on Sunday that there had been "very positive discussions with Hamas, and Countries from all over the World" on a proposed ceasefire in the Gaza Strip.

"These talks have been very successful, and proceeding rapidly," Trump added. Technical teams will meet again on Monday in Egypt "to work through and clarify the final details," the president said.

"I am told that the first phase should be completed this week, and I am asking everyone to MOVE FAST," Trump wrote.

-ABC News' Lalee Ibssa

Hundreds of thousands of people around the world staged protests in support of Palestinians in Gaza on Sunday.

In Amsterdam, organizers estimated that 250,000 people marched in the rain. Many wore red as a symbolic "red line" against Israel's blockade of Gaza.

In Ankara, Turkey, thousands marched, wearing red and chanting in support of intercepted flotilla activists who were trying to bring aid to Gaza.

In Karachi, Pakistan, thousands of people marched through the streets carrying pamphlets and flags.

--ABC News' Victoria Beaule

Leaving the White House for the Navy’s 250th celebration on Sunday, President Donald Trump continued to celebrate his Gaza peace proposal while admitting that negotiations are still ongoing.

“They're in negotiation right now as we speak, they've started the negotiation. It will last a couple of days. We'll see how it turns out. But I'm hearing it's going very well,” Trump said.

Trump was pressed by a reporter on his faith in a Palestinian Authority to control Gaza without Hamas influence, getting mad at the reporter for doubting the deal.

“Well, it's a great deal for Israel, and it's a great deal for everybody. And you want to get hostages back, right? You want them back? Or do you not want them back?” Trump quipped at the reporter who said she worked for an Israeli media company.

“It's a great deal for Israel. It's a great deal for the entire Arab world, Muslim world, and world. So we're very happy,” Trump said.

Trump’s irritation comes as Axios reported Sunday morning, Trump got mad when Netanyahu said there was nothing to celebrate after Trump called him to discuss Hamas’ “yes” to his peace proposal.

“I don’t know why you’re always so f---king negative. This is a win. Take it,” Axios reported.

-ABC News’ Lalee Issa