Smith missed two practices this week with a sore right ankle. He says he was only retaliating when Incognito tried to twist his ankle after the whistle.
"If you're going strictly by the rule book, me kicking him was breaking the rules," Smith said Friday. "But I want them [the NFL] to look at why I was kicking him, trying to get him off of my ankle. You see on the film, the moment my ankle came free, I stopped. I was just trying to get my ankle free from him mauling it."
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After Sunday's game, Incognito said he was innocent of wrongdoing.
"There was a lot of whining going on out there, and it went to the refs, and then the whining continued to the media after the game," Incognito said Monday.
Incognito, who has carried what he says is an outdated reputation as a dirty player, said the complaint about twisting Smith's ankle stemmed from a play where the Dolphins fumbled.
"He was getting up and trying to go for the ball," Incognito said, "so I pretty much tackled his legs."
The Texans (1-0) play at Jacksonville (0-1) on Sunday. Smith practiced on Friday and coach Gary Kubiak expects him to play against the Jaguars.
Smith says he plans to appeal.
"It's very disappointing, whenever you lose money," said Smith, who had a career-high 6½ sacks last year. "Nobody wants to lose money, especially $21,000. That could be going to my daughter or son's trust fund, or something. That's a pretty penny, and nobody would like to get [fined] that kind of money, especially when I felt like I was defending myself."
Smith was fined $7,500 last season for pulling off Baltimore guard Andre Gurode's helmet in a game against the Ravens.