The Rockets lost 99-81 to the Grizzlies at the FedExForum on Saturday night, which followed a defeat to the same opposition at the Toyota Center the previous night.
"The last two games we've been terrible offensively," Parsons told reporters after the latest defeat. "Their pace works for them.
"They are physical. They grab. They reach. They hold. When you do that so much, they are not going to call every single foul."
The Rockets will look to recover from successive defeats when they host the San Antonio Spurs on Tuesday.