"It is now prohibited to approve lending or credit to any Syrian person or entity in the exploration, production and refining business of crude oil," the economy ministry said in a statement.
"It is also prohibited to deliver or sell to the Syrian central bank coins or new bank notes in Syrian currency," it added.
The impact of these new measures are expected to be minimal as there are no known Swiss investments in Syria's oil industry.
Switzerland had earlier already imposed sanctions against the regime of President Bashar al-Assad, targetting it with travel embargos and asset freezes on 54 individuals. About 12 firms have also been hit.
The economy ministry had also announced an embargo on the import, sales and transport of Syrian oil and oil products "due to the relentless repression imposed by the Syrian security forces."
Syrian assets frozen in Switzerland currently reach 45 million francs ($50 million).
The office of the UN High Commissioner for Human Rights in Geneva has said the death toll from the Syrian government's bloody crackdown on anti-regime protests has risen to more than 2,700 since March 15th.