The Post said activists believe the sanctions make it more difficult for opposition groups to get access to technologies to evade electronic surveillance or censorship.
The Obama administration's sanctions have forced many Western companies, including technology firms, to end business with Syria and Iran -- isolating those governments, the Post said.
But the sanctions also have blocked opposition access to e-mail, blogs and security tools to prevent user activity from being traced, the newspaper said.
"We are fighting on two sides: the side of the regime, and the side of the sanctions," Dlshad Othman, a Syrian activist who works with opposition groups across the region, told the Post.
"And sometimes we're not successful. So people take risks, and they are filming and uploading pictures without protection, so the regime can easily arrest them or even kill them."
"The thing about the sanction effort is that ... they've actually done more harm than good," Jillian C. York of the Electronic Frontier Foundation, said. EFF is a rights group that was among the signatories to an open letter this summer that called on large Internet companies to apply for export licenses.
U.S. officials said they have issued general licenses for the export of "free, mass-market personal communications software and services," the Post said, and have also issued guidance on what is permitted.