Antonio Guterres advised Lebanon's official government "to take all measures necessary to prohibit Hezbollah and other armed groups from acquiring weapons and building paramilitary capacity."
According to Guterres, military actions violate a 2004 UN Security Council resolution ordering all Lebanese militias to disarm.
"In a democratic state, it remains a fundamental anomaly that a political party maintains a militia that has no accountability to the democratic, governmental institutions of the state but has the power to take that state to war," he said as quoted by The Times Of Israel.
READ MORE: ‘Lebanon Equals Hezbollah': Israeli Security Cabinet Minister on Lebanese Vote
On May 6, Lebanon held its first general election since 2009. Within the nine-year period, the nation's parliament extended its mandate three times under the pretext of political instability. On May 7, Hezbollah Secretary-General Hassan Nasrallah said that a new government would unite the army, the Lebanese people, and the Hezbollah resistance.
The deputy leader of Hezbollah has admitted that it was the movement's fighters that launched an attack, targeting Israel earlier this month as a "counteraction strategy" to the Jewish state's policy.
READ MORE: Israel 'Must Destroy Any Trace of Iran in Syria, Put Genie in Bottle' – Minister
On May 10, the Israeli Air Force hit dozens of what it described as Iranian targets in Syria after 20 rockets had been fired at the IDF positions in the Golan Heights, which had been occupied by Israel during the 1967 Six-Day War and later annexed the territory in 1981.
Damascus has stated that Syria would counter all attacks by the Israeli forces on its sovereign territory and will not hesitate to strike Israeli military targets as it has a right to self-defense. When commenting on the latest Israeli attack in Syria, the Iranian Foreign Ministry slammed the move as "an act of aggression" and a breach of the Arab country's sovereignty.