Donald Trump said he hoped to reach phase two of the Gaza peace plan "very quickly", as he warned Hamas would have "hell to pay" if it did not disarm quickly.

The US president, whose 20-point peace plan requires the militant group to disarm, made the comments as he met Israeli Prime Minister Benjamin Netanyahu in Florida for talks on Monday.

During a press conference with Netanyahu after their meeting, Trump said Israel had "lived up to the plan 100%", despite continuing attacks by its military in Gaza.

The US president also said his country could support another major strike on Iran were it to resume rebuilding its ballistic missile or nuclear weapons programmes.

Asked how quickly Hamas and Israel should move to phase two of the peace plan, Trump said: "As quickly as we can. But there has to be disarmament."

Speaking about Hamas, he said: "If they don't disarm as, as they agreed to do, they agreed to it, and then there will be hell to pay for them.

"They have to disarm in a fairly short period of time".

Trump also said reconstruction in Gaza could "begin pretty soon".

The Gaza peace plan came into effect in October. Under the second phase, a technocratic government would be established in the devastated territory, Hamas would disarm and Israeli troops would withdraw. The reconstruction of Gaza would then begin.

But critics have suggested Netanyahu could seek to delay the process of the plan and instead push for Hamas to disarm before Israeli troops withdraw.

The Israeli prime minister has been accused of not wanting to engage seriously with the issue of a political future for Palestinians.

Hamas officials have said a full disarmament should take place alongside progress towards an independent Palestinian state.

Asked if he was concerned Israel was not moving quickly enough to phase two of the plan, Trump said it had "lived up to the plan".

"I'm not concerned about anything that Israel's doing, I'm concerned about what other people are doing or maybe aren't doing," he added.

Since the ceasefire came into effect, at least 414 Palestinians have been killed by the Israeli military in Gaza, according to the Hamas-run health ministry.

The Israeli military, which controls more than half of Gaza, has said it has only opened fire in response to ceasefire violations. It has blamed Hamas for the killings of three Israeli soldiers over the same period.

During the press briefing, Trump also warned that the US would launch further attacks on Iran if it was found to be using different sites to develop nuclear weapons.

In June, Trump claimed US air and missile strikes "obliterated" Iran's nuclear facilities. Iran has denied seeking to develop nuclear weapons.

"I hope they're not trying to build up again, because if they are we're going to have no choice but to eradicate that build up," he said.

Trump said he "had been reading" that the country was using "possibly different sites" to those targeted in summer.

Iran, which fought a 12-day war with Israel in June, on Monday denounced the reports as a "psychological operation" against Tehran.

It said it was fully prepared to defend itself, and warned renewed aggression would "result in harsher consequences" for Israel.

Trump and Netanyahu's talks also focused on other regional tension points, including Syria and the Hezbollah militant group in Lebanon.

Netanyahu said on Monday that Israel was keen to ensure a peaceful border with Syria, and Trump said he hoped Israel would get along with President Ahmed al-Sharaa, who took power after longtime strongman Bashar al-Assad was deposed last year.

Israel has been suspicious of the new leader, who was once a member of al-Qaeda, and bombed government buildings in Damascus in July.

"Well, I hope he's [Netanyahu] going to get along with Syria because the new president of Syria is working very hard to do a good job," Trump said.

"He really is. I know he's a tough cookie. And, you know, you're not going to get a choir boy to lead Syria."

Trump signed an executive order in June to end US sanctions against Syria.