During the event at the White House, featuring a group of around two dozen rabbis and leaders of Jewish organisations, Biden also warned Iran to "be careful".
The travel advisory for the West Bank has also been raised to level 3, while the advisory for Gaza remains at the most severe - "Level 4: Do Not Travel."
Israel Prime Minister Benjamin Netanyahu on Wednesday (local time) spoke with US President Joe Biden again amid the ongoing war with Hamas, and thanked the leader for his "unequivocal" support to the nation.
Sullivan's remarks came after US President Joe Biden denounced the attacks on Israel as "pure unadulterated evil," saying the stated purpose of the terrorist organisation Hamas is "to kill Jews."
US President Joe Biden said that in the wake of the deadly Hamas attack on Israel, the local and federal law enforcement partners in the US cities are closely monitoring for any 'domestic threats'.
"Israel is at war. We didn't want this war. It was forced upon us in the most brutal and savage way. But though Israel didn't start this war, Israel will finish it," Israeli Prime Minister Benjamin Netanyahu said in an address to the nation.
The deceased from the deadly attack launched on Israel by Hamas, includes at least nine US citizens, US National Security Council spokesperson said, CNN reported on Monday.
Blinken had previously responded to Republican criticisms of the deal made by the Biden administration with Iran, which involved unfreezing USD6 billion in funds in exchange for five US prisoners held in Iran.
Earlier, PM Netanyahu also spoke with other world leaders including German Chancellor Olaf Scholz, Ukrainian President Volodymyr Zelenskyy, Italian Prime Minister Giorgia Meloni, and British Prime Minister Rishi Sunak who also held up with the Israeli side for defending its country.
US President Joe Biden has said the US stands with Israel in the face of terrorist assaults by the Hamas Group and will make sure the country has the help its citizens need.