They told The National that this scenario featured prominently over the last 48 hours in high-profile meetings in Amman between King Abdullah and Palestinian leader Mahmoud Abbas, and between the king and US Secretary of State Antony Blinken.
"The concern in Jordan is that Hamas has more up its sleeve," said one of the diplomats, who requested anonymity. "Hamas could mount an operation against Israelis in the West Bank that could expand the war in a major way."
"In this case, people fleeing the violence have no place to go except towards Jordan."
For decades Jordanian authorities have cautioned against more Israeli pressure on the Palestinians resulting in another wave of refugees to the kingdom.
More Palestinian refugees would upset a social balance overseen by the king between those who came originally from Palestine since 1948, and tribes who were a cornerstone of Jordan's founding as a British protectorate in 1921.
Most of Jordan's 10 million population are descendants of refugees who fled the conflict surrounding Israel's creation in 1948 and Israeli expansion after the 1967 Middle East War.
The war in Gaza started on October 7 with a surprise attack by the Iran-backed Palestinian militant group Hamas on areas held by Israel. The attack killed more than 1,300 people, mostly civilians.
Israeli retaliation strikes killed more than 2,200 people in Gaza, also mostly civilians. More than 40 people have been also reportedly killed in the occupied West Bank in Palestinian-Israeli hostilities.
US State Department spokesman Mathew Miller said that when Mr Blinken met the Jordanian king on Friday, the two men discussed efforts to "prevent the conflict from widening." King Abdullah had met Mr Abbas the day before.
Hamas called the attack on Israel the Al Aqsa Flood, in reference to the mosque in occupied East Jerusalem, which is of immense religious importance.
Another diplomat said by linking the operation to Al Aqsa, Hamas is "itching for the conflict to spread."
"You could see the gravity of the situation, how sombre the king appeared when he met Mr Abbas, said another diplomat.
"He is looking at the spectre of a nightmare scenario," he said. "The Jordanians are hoping that the Palestinian Authority will not be swept away if the West Bank becomes a war theatre."
The king's message to Mr Abbas, the diplomat said, was that Jordan will do everything to help him.