The United Nations has condemned an intense wave of Israeli airstrikes on Syria as Israel said its forces were on the ground in Syria to protect the Druze minority sect following days of clashes with Syrian pro-government gunmen.

Israel escalated its military campaign in Syria by launching airstrikes in the Damascus countryside and issuing threats against the Syrian leadership, citing unrest in Druze-populated districts earlier this week.

Israel's PM says it will "not allow any threat" to the minority in Syria after sectarian clashes in which dozens were killed.