Armed factions close to Iran have threatened to attack US interests over Washington's support for Israel since Hamas militants killed more than 1,400 people in a shock cross-border attack from Gaza on October 7.

Israel's retaliatory bombardment of Gaza has killed more than 5,000 people -- most of them civilians -- according to the Gaza health ministry. The deaths have sparked widespread anger across the Middle East.

"Between October 17th and the 24th, US and coalition forces have been attacked at least 10 separate times in Iraq and three separate times in Syria," Pentagon spokesman Brigadier General Pat Ryder said, referring to the international coalition against the Islamic State (IS) jihadist group.

The attacks were conducted with a "mix of one-way attack drones and rockets," Ryder told journalists, describing the tally of the strikes as "initial numbers."

He did not identify the specific organizations responsible, but said that "the groups conducting these attacks are supported by the IRGC and the Iranian regime" -- a reference to Tehran's Islamic Revolutionary Guard Corps.

Many of the attacks have been claimed by a group calling itself the "Islamic Resistance in Iraq" in Telegram channels affiliated with Shiite factions close to Iran.

"What we are seeing is the prospect for more significant escalation against US forces and personnel across the region in the very near term coming from Iranian proxy forces, and ultimately from Iran," Ryder said.

The United States has some 900 troops in Syria and 2,500 in Iraq as part of efforts to combat IS, which once held significant territory in both countries but was pushed back by local forces supported by international air strikes.