Police in New York, where there are locations sensitive to both Israeli and Palestinian interests, are adjusting patrols in response to the situation in Israel.

"The NYPD's Counterterrorism and Intelligence Division consistently work at a level of high alert. When events from around the world could possibly affect NYC or we get Intel on a threat to NYC, we always increase our presence around houses of worship and certain areas when these conflicts arise," the NYPD said in a statement.

The Beverly Hills Police Department also said it increased security and patrols around Jewish institutions in the City and continues to work closely with law enforcement partners in the region to ensure public safety.

Law enforcement and Homeland Security officials will be assessing the potential for residual violence in the U.S.

Increased security around Jewish facilities and on university campuses -- particularly where there is a history of confrontational interactions -- is to be expected. Increased attention is expected to be paid to potential cyber threats and online activities intended to inspire violence by Iran, Hezbollah and other extremists threat actors.

-ABC News' Aaron Katersky and Alex Stone

United Airlines, American Airlines and Delta Airlines announced they will suspend operations to Israel Saturday night following unrest in the region. After two departures scheduled for Saturday, United's future operations will be suspended until conditions allow them to resume, the airline said.

"The safety of our customers and crew is our top priority. We are closely monitoring the situation and we are adjusting flight schedules as required," the carrier told ABC News.

American Airlines said it will temporarily suspended operations to and from Tel Aviv and will continue to monitor the situation, adjusting its operations as needed.

"American Airlines has temporarily suspended operations to and from Tel Aviv, Israel (TLV) [Saturday] and [Sunday], and has issued a travel alert providing additional flexibility to customers whose travel plans are affected. We will continue to monitor the situation with safety and security top of mind and will adjust our operation as needed," American Airlines said in a statement.

Delta Air Lines has canceled scheduled flights in and out of Tel Aviv this weekend. The airline said its working to "safely transport Delta people back to the U.S. and will work with the U.S. government as needed to assist with the repatriation of U.S. citizens who want to return home."

-ABC News' Amanda Maile and Sam Sweeney

President Joe Biden spoke with Israeli Prime Minister Benjamin Netanyahu, telling him that the U.S. "condemns" Hamas' assault on Israel.

"I made clear to Prime Minister Netanyahu that we stand ready to offer all appropriate means of support to the Government and people of Israel. Terrorism is never justified. Israel has a right to defend itself and its people. The United States warns against any other party hostile to Israel seeking advantage in this situation. My Administration’s support for Israel’s security is rock solid and unwavering," Biden said in a statement.

Biden also extended his condolences for lives lost and wished those wounded a "swift recovery."

"My team and I are tracking this situation closely, and I will remain in close touch with Prime Minister Netanyahu," Biden said.

U.S. Secretary of State Antony Blinken issued a statement condemning Hamas' attack on Israel, saying the U.S. will "remain in close contact with our Israel partners."

"The United States unequivocally condemns the appalling attacks by Hamas terrorists against Israel, including civilians and civilian communities. There is never any justification for terrorism. We stand in solidarity with the government and people of Israel, and extend our condolences for the Israeli lives lost in these attacks," Blinken said in a statement.

-ABC News' Shannon Crawford

In remarks with Israeli Prime Minister Benjamin Netanyahu, Secretary of State Antony Blinken said at least 25 Americans had now been confirmed dead in Israel.

Netanyahu described some of the atrocities committed by Hamas.

"Hamas has shown itself to be an enemy of civilization: The massacring of young people in an outdoor music festival, the butchering of entire families, the murder of parents in front of their children and the murder of children in front of their parents. The burning of people alive, the beheadings," he said.

"Hamas should be treated exactly the way ISIS was treated," he said. "They shouldn't be spit out from the community of nations. No leader should meet them. No country should harbor them. And those that do should be sanctioned."

Blinken said he was speaking not only as an American diplomat, but as a Jew, a husband and a father of young children, saying it was impossible for him to look at photos of families killed "and not think of my own children."

"The same time that we've been shocked by the depravity of Hamas, we've also been inspired by the bravery of Israel citizens," he said. "The grandfather who drove over an hour to a kibbutz under siege, armed only with a pistol and rescued his kids and grandkids. The mother who died shielding her teenage son with her body, giving her life to save his -- giving him life for a second time."

Blinken remarked that some U.S. aid had already been delivered, and that more military aid was on his way. He said the administration would work with Congress to meet Israel’s additional needs and that bipartisan support for Israel was "overwhelming."

The secretary called on world leaders to condemn Hamas.

Blinken also reiterated that Israel "has the right -- indeed, the obligation -- to defend itself" but that it was "so important to take every possible precaution to avoid harming civilians."

-ABC News' Shannon Crawford