Ryan Clark reveals what he had to do to clear concussion protocol when he played as the Steelers navigate the same process with Mason Rudolph. (1:01)

OWINGS MILLS, Md. -- Baltimore Ravens safety Earl Thomas II told ESPN that he was fined $21,000 by the NFL for his hit on Pittsburgh Steelers quarterback Mason Rudolph.

Thomas said he plans to appeal the fine.

Thomas' helmet connected on Rudolph's chin in Sunday's 26-23 overtime win in Pittsburgh. Rudolph suffered a concussion and appeared to get knocked out on the play. Thomas wasn't initially flagged, but officials later penalized him for roughing the passer.

Thomas reached out to the second-year quarterback by calling him and texting him this week. Rudolph didn't respond, according to Thomas.

"I wanted to him to know that I didn't do it on purpose," Thomas said. "That's all I wanted him to know."

Rudolph remains in concussion protocol and has been limited in practice this week. It's uncertain whether he'll play Sunday against the Los Angeles Chargers.

Ravens coach John Harbaugh said it's clear that Thomas wasn't looking to hurt Rudolph.

"I see Earl trying to pull off. There's no question about it when you watch the tape," Harbaugh said. "He goes in there, and as he gets close, he's running to the ball. Mason is scrambling and going, and [Thomas] is running to the ball, playing fast, and he tries to pull out. It's clear. So I respect him for that. It's just an unfortunate collision."