The rhetoric has since been repeated by others in the administration, with National Security Advisor Jake Sullivan telling reporters that they believe militia groups across the region "pose an urgent threat" and could "choose to try to exploit" the situation.
"We have been sending clear warnings that doing so will result in a firm response and consequences from the United States," Sullivan said Tuesday.
National Security Council spokesman John Kirby told reporters Wednesday there's a "long list of actors in the region that are hostile to Israel," including Hezbollah, the Iran-backed Lebanese militant group.
The administration has also offered its full support to Israel, with Defense Secretary Lloyd Austin telling reporters in Brussels on Thursday that the U.S. is not placing conditions on the military aid it's providing to Israel. The U.S. additionally moved a carrier strike group into the eastern Mediterranean as part of its deterrence measures.
"We're sending a loud and clear message: The United States is ready to take action should any actor hostile to Israel consider trying to escalate or widen this war," Kirby said Wednesday.
How impactful those gestures will be on the raging war remains uncertain. The U.S. has limited leverage in the region, though does need to be careful to not further escalate the conflict, foreign policy experts said. The Biden administration is also likely keen to not get heavily involved, experts said.
"If Hezbollah or the Islamic Revolutionary Guard Corps or some other militant group from a neighboring country decides to get involved and attack Israel at this time, I don't think the United States is going to do anything more than it's currently doing -- which is offering Israel whatever it needs to defend itself," Ralph Carter, a professor of political science at Texas Christian University, told ABC News.
Biden has historically been "cautious" in sending U.S. troops into battle, Carter said. "His experience in Washington over 40 years or more suggests that once you start something like that, you have no idea where it's going to end."
Kirby said Thursday that there are no active plans or intentions to send U.S. troops to join a potential ground war in Israel and Gaza. The U.S. has deployed its largest carrier group, the USS Gerald R. Ford, to the region as an act of deterrence, officials said.
"The United States has moved military assets in the region, but I really do find it doubtful that the Biden administration really wants to get heavily involved militarily," Russell Lucas, a professor of international relations and global studies at Michigan State University, told ABC News.
Israel's powerful military is also capable of defending itself against Hamas and other militant groups, experts noted, which may limit what it needs from the U.S. and act as another deterrent.
"The requirements on the U.S. defense industry I think are maybe not as heavy as they might be if we were talking about a weaker ally," Adria Lawrence, the Aronson Associate Professor of International Studies and Political Science at Johns Hopkins University, said during a public briefing on the conflict.
In recent days there have been some limited military engagements on Israel's northern border with Lebanon, though Hezbollah may be deterred from getting drawn into a larger conflict with Israel, experts said.
"They will pay dearly for entering the conflict," Lucas said. "I think most actors [in the region] know that at the end of the day, the most military-capable actor is Israel, so there is a deterrence factor."
Given Israel's known military prowess, the Biden administration's rhetoric may be stronger than necessary, Lucas said.
"I think it's more the Biden administration is aiming especially at the domestic audience -- trying to reassert that kind of bully pulpit of the commander-in-chief role, especially in the face of perhaps critiques from the Republican Party that Biden isn't strong enough," he said.
At the same time, the U.S. does need to be careful about making any threats, experts said.
"Words matter and if President Biden's making a commitment and making kind of an implicit threat, he needs to remember the risks that are inherent in making a red line," Lucas said. "President Obama's red line in Syria -- do not use chemical weapons -- that was then not followed up was viewed as one of Obama's biggest foreign policy failures."
Sarah Parkinson, the Aronson Assistant Professor of Political Science and International Studies at JHU, said during the university's briefing that these comments by U.S. officials "will likely embolden extremists on both sides" and prolong the conflict.
Following Biden's remarks, Hezbollah said they will not back down and are "ready for confrontation," while the top leader of the Islamist armed organization Houthis in Yemen said that if the U.S. intervenes militarily in Gaza, they will send munitions and fighters to support Hamas.
In efforts to deescalate the conflict, the U.S. could help mobilize other countries in the region, according to James Steinberg, the dean of the School of Advanced International Studies at JHU and former Deputy Secretary of State during the Obama administration.
"It's not that the United States itself is going to broker a resolution of this, but it can engage others, all of whom have a stake in not seeing the situation escalate," Steinberg said during the university's briefing, noting the discussions that have been taking place between the U.S. and Saudi Arabia, the UAE and others.
Secretary of State Antony Blinken told reporters Thursday at a press conference in Israel that they are working with their partners in the region to ensure "that there will not be a second front or a third front."
Steinberg said a wider war "can't be ruled out," and the effectiveness of the U.S.' response to deescalate is "uncertain" -- likening it to its support of Israel in 1973 during the Yom Kippur War.
"Here as then, the United States has limited impact and limited leverage," he said. "Perhaps even less so today than it did in 1973."