U.S. President Barack Obama told Lebanese President Michel Suleiman on Monday that he was concerned about the involvement of Lebanese Hizbullah terrorists in the fight in Syria to support President Bashar al-Assad.

According to the White House, Obama and Suleiman spoke by telephone after about 30 Hizbullah terrorists, including one senior commander, were killed in fierce fighting in the Syrian town of Qusayr.

“President Obama expressed his appreciation to President Suleiman and the Lebanese people for keeping Lebanon’s borders open and hosting refugees from Syria, and pledged continued U.S. support to help Lebanon manage this challenge,” the White House said in a statement summarizing the two leaders’ phone call.

The statement said the two agreed that “all parties should respect Lebanon’s policy of disassociation from the conflict in Syria and avoid actions that will involve the Lebanese people in the conflict.”

The Hizbullah official who was killed Sunday was identified as Fady al-Jazzar, who is considered to be a major Hizbullah leader and was imprisoned in Israel until he returned to Lebanon in a prisoner-exchange deal with Israel.

Initially, the Lebanese-based Hizbullah denied it was assisting Assad quell the rebellion against him, but last year as the ongoing civil war in Syria continued, the terror group led by Hassan Nasrallah publicly offered to place itself at Assad’s disposal.

Hizbullah’s involvement in the Syrian civil war has been criticized both by the Syrian rebels as well as by political forces in Lebanon which oppose Hizbullah. The Syrian civil war has spilled into Lebanon on more than one occasion.