Mr Juppe has joined the UN envoy to Syria Kofi Annan in calling for a rapid increase in the speed of the deployment of UN observers.
Violence has continued despite a plan Mr Annan calling on Damascus to withdraw troops and heavy weapons from cities, the BBC reports.
Mr Juppe said 300 UN monitors should be deployed in Syria within two weeks.
However, if the peace plan failed a Chapter Seven resolution would be needed to stop "this tragedy".
Chapter Seven resolutions allow for action that could be backed by force.
The BBC reports there are concerns that such a resolution would be vetoed by Russia and China - which have blocked previous attempts to impose UN sanctions on Syria.
Attacks in Hama
Up to 70 people have been killed in an attack on a house in Hama, according to Syrian activists. They said several houses in the Masha at-Tayyar district in southern Hama were destroyed by a big explosion.
However, state media said 16 people died in the blast in a house used as a bomb factory by "armed terrorist groups".
Following the blast, activists posted video on the internet showing a scene of devastation, with bodies being pulled from the rubble.
But the BBC says the reports cannot be independently verified, owing to government restrictions on foreign media.