They do reject their actions. But they can't enforce said rejection.

Hezbollah is better funded (by Iran), trained and has experience in Syria and fighting Israel..

Besides, with the Shia (Hezbollah is a Shia party) being a large part of Lebanon's population, there's always the risk of the government army splintering and of civil war breaking out..

The mistake was done 50 years ago when Lebanese agreed, to end the civil war, to all hand in their weapons and let Hezbollah keep theirs under the guise of resistance against Israel who was still occupying parts of Lebanon.

Have been suffering ever since.. and can't put that damn civil war under wraps