Dozens of Israeli tanks and armoured vehicles surrounded the Nasser Hospital in Gaza Tuesday, where thousands of displaced people have sought refuge from the fighting, witnesses said.

Witnesses told AFP that shots were being fired at the sprawling complex in the southern city of Khan Younis, but no raid was as yet taking place.

Prime Minister Benjamin Netanyahu on Tuesday vowed to press ahead with Israel's offensive and blasted a U.N. Security Council resolution calling for a pause in the fighting, saying it had emboldened Hamas to reject a separate proposal for a cease-fire and hostage release.

As the war in Gaza grinds through a sixth month, each side has publicly insisted that its own idea of victory is in reach and rejected international efforts to stem the bloodshed.

At least nine pro-Tehran fighters, including an Iranian Revolutionary Guards commander, were among 13 people killed in air strikes in eastern Syria on Tuesday, a war monitor said.

"Nine pro-Iranian fighters, including a Revolutionary Guards commander, were killed in air strikes targeting the villa they were staying in, which served as a communications centre," the Syrian Observatory for Human Rights said.

Hamas leader Ismail Haniyeh was in Tehran on Tuesday for talks with Iranian officials, state media reported, a day after the U.N. Security Council called for a ceasefire in the group's war with Israel.

"Hamas bureau chief Ismail Haniyeh, during his trip to Tehran on Tuesday, will meet with Iranian Foreign Minister Hossein Amir-Abdollahian," Iran's official IRNA news agency said, adding that he will also meet with other senior officials.

The U.N. Security Council has called for an immediate ceasefire in Gaza five months into the grinding war, despite Israel's ally the United States abstaining.

Here are some reactions to the resolution to halt fighting over the Muslim holy month of Ramadan with an aim for a "lasting" truce, which drew rare applause at the Security Council:

Israeli Prime Minister Benjamin Netanyahu has canceled a planned visit to Washington by a high-level delegation to protest Monday’s U.N. Security Council decision calling for an immediate cease-fire in Gaza.

The resolution passed 14-0 on Monday after the U.S. decided not to use its veto power and instead abstained. The U.S. has previously vetoed three resolutions demanding a cease-fire.

Hamas welcomed a U.N. resolution Monday calling for a ceasefire in its war against Israel, and said it was ready to negotiate the release of hostages in exchange for Palestinian prisoners.

"Hamas welcomes the United Nations Security Council's call today for an immediate ceasefire" in the Gaza Strip, the militant group said, adding: "We also affirm our readiness to engage in an immediate prisoner exchange process that leads to the release of prisoners on both sides."

The U.N. Security Council for the first time on Monday demanded a ceasefire in Gaza, with the United States, Israel's ally which has vetoed previous bids, abstaining.

The resolution, which demands an "immediate ceasefire" for the ongoing Muslim holy month of Ramadan that leads to a "lasting" truce, went through, with all other 14 Security Council members voting yes.

Aid groups that visited a packed Gaza hospital described an “unimaginable” situation in which large open wounds were left untreated.

An emergency medical team organized by three aid groups spent two weeks carrying out surgeries and other care at the European Gaza Hospital near Khan Younis. The southern city has seen heavy fighting between Israeli forces and Palestinian militants since the start of the year.

China said Monday it supported a new draft resolution at the U.N. Security Council on an "immediate" ceasefire in Gaza, after it and Russia vetoed an earlier text proposed by the United States.

"China supports this draft resolution and commends Algeria and other Arab countries for their hard work in this regard," foreign ministry spokesperson Lin Jian said, adding: "We hope the Security Council will pass it as soon as possible and send a strong signal for the cessation of hostilities."