The new rules came into effect on Tuesday. The reason cited is "public interest".
The announcement comes six months after the extremist Islamist group Hayat Tahrir al-Sham (HTS), led by current interim leader Ahmed al-Sharaa, overthrew the regime of long-time dictator Bashar al-Assad.
Outside of beach areas, women are required to wear "loose-fitting clothing" while men are forbidden from going topless. However, few women in the largely conservative Syria have worn "revealing" clothing since the beginning.
The new rules come with exceptions. Private beach clubs and "luxurious" facilities do not need to follow the guidelines, according to the Tourism Department in Damascus. There, Western-style swimwear is allowed – "within general moral boundaries".
In social media, the government's clothing decree has been met with mixed responses. Some express increased concern over their personal freedom under the new authorities, which came to power in December.
The Islamist regime in Damascus has, however, sent signals of a somewhat softer stance than feared. For example, alcohol is allowed to be served at restaurants and bars in Damascus areas with a Christian majority population.