"There was always something (between Watson and Felton)," Grint, 31, said. "There was a little bit of a spark."
Grint, despite hoping not to start any rumors, admitted that there "were some sparks" between the two actors.
"But we were kids. It was like any kind of playground romance," he said.
Grint describes his time on set, however, as "spark-free."
He also admitted to not watching any of the eight "Harry Potter" films during his time working on them; only recently did he watch "Harry Potter and the Sorcerer's Stone."
"You watch us grow up through all the awkward teenage stages, and it's not something that I've ever really wanted to revisit," Grint confessed as to why he'd never seen any of them. "It was a great experience, and I've got great memories."
The "Snatch" star also discussed the possibility of a "Harry Potter" reboot.
"It was an amazing period of our lives, but I don't think any of us would be keen to jump back into it just yet," he admitted. "But never say never."