Hezbollah denied any responsibility for the strike, the deadliest in Israel or Israeli-annexed territory since the start of the conflict in Gaza.
In a written statement, Hezbollah said: "The Islamic Resistance has absolutely nothing to do with the incident, and categorically denies all false allegations in this regard".
Hezbollah had earlier announced several rocket attacks targeting Israeli military positions.
"They were playing soccer, they heard sirens they ran to shelter...it may take them like 15 seconds (to reach the shelter).
Hamas has also carried out rocket attacks on Israel from Lebanon, as has the Lebanese Sunni group, the Jama'a Islamiya.
The Israeli military said its aircraft had targeted a military structure belonging to Hezbollah, after identifying a militant cell entering the building.
Hezbollah claimed at least four attacks, including with Katyusha rockets, in retaliation for the Kfarkila attacks. »