"These restrictive measures have been decreed due to the violent repression that the army and the Syrian security forces have enforced for two months to snuff out peaceful demonstrations by the population," the economy ministry said.
Bern had already blocked assets worth 27 million francs ($31.7 million) belonging to Assad and 22 other individuals.
On Wednesday it added several others, including the president's cousin and head of presidential security, Zulhima Shalish, and former defence minister Ali Habib Mahmud, to the embargo list.
Four companies or entities that finance the regime have also been placed under sanctions.
Rights groups say the regime's crackdown has killed 1,827 civilians since mid-March, while 416 security forces have also died.