The bill would ban TikTok in the United States if its owner ByteDance fails to divest the app over the next nine months
Users failed to access the official site, ictd.gov.bd, for hours on Saturday afternoon.
An ICT Division spokesperson said their initials findings suggested Indian hackers were behind the cyber attack.
After Bangladesh's defeat against India in Thursday's ICC Champions Trophy semi final, a Facebook page titled 'Cyber 71' claimed they had hacked some 100 Indian sites.