"We strongly condemn Hezbollah's attack today near the border," State Department spokeswoman Jen Psaki told reporters.
She said that while Israel has the right to defend itself following the attack, “our preference is to reduce the tensions and the violence and the back-and-forth from here.”
The attack in the disputed Shebaa Farms area killed two Israeli troops and wounded seven others.
A UN peacekeeper, part of a Spanish contingent, was also killed, according to a Lebanese security official.
The attack comes 10 days after Hezbollah accused Israel of killing six of its fighters, along with six Iranians, in an air strike in Syria’s southern city of Quneitra.
In a statement, the Shiite movement said that one of its units, dubbed the "Quneitra Martyrs' Group,” had attacked an Israeli military convoy, leaving several Israeli troops dead or injured.
The Israeli army said Wednesday that it had shut its border with Lebanon, fearing an escalation of violence.
An army source said the Israeli military decided to launch an inquiry into what he described as "two mistakes" that led to the death of the two soldiers in the attack.