Johnson, who will miss his fifth straight game, was injured in the Texans' 17-10 win over Pittsburgh in Week 4. He developed soreness after a hard workout on Monday that raised concern.
"We kind of had a little setback," Johnson said.
Johnson sat out practice all this week, though he stretched and ran on a separate field Friday. Houston coach Gary Kubiak said Johnson is "very close," but added, "Obviously, he's not ready to go yet."
Johnson met with doctors and plans to test the injury in another workout next Monday.
"Just have to keep working hard and stay positive," Johnson said. "At the same time, even though I was sore for a few days, I still think we're headed in the right direction."
The Texans (5-3) are 2-2 without Johnson this season. Kubiak would not speculate on Johnson's availability for the Texans' game at Tampa Bay on Nov. 13.
Johnson acknowledged that he expected to be fully healed by now. He underwent a minor procedure after he was hurt, and was back at practice last week leading up to Sunday's victory over Jacksonville.
"Just like everybody else, I wish this process would be a lot faster than what it's been," he said.
He was relieved that the "setback" occurred on Monday, rather than later in the week.
"If it wouldn't have happened Monday, then it probably could've happened on Wednesday in practice," Johnson said. "Eventually, I was going to find out, whether it was Monday or Wednesday or whenever I ran. It happened on Monday. I sat down for a few days and just did all the treatment. I didn't start back running until (Friday), and the day went pretty good.
"We're just going to keep working, and hopefully, it'll get better sooner than later."
Johnson, a five-time Pro Bowl selection, was Houston's leading receiver through the first four games, with 25 catches for 352 yards and two touchdowns. He wants to be careful now not to return to action too soon.
"If I can't go out and be myself, then there's no reason for me to be out there," Johnson said. "It doesn't help the team. This isn't about me, this is about the team. If I can't go out and help the team, then I'm not going to be out on the field."
The Texans have their bye week after playing the Buccaneers in Week 10. Johnson says he has no target date in mind for his return.
"At first, I just felt like I'd just miss a couple of games and I'd be back out there," he said. "It just all depends on how your body responds. Right now, I really can't set a date."
Kubiak also said safety Danieal Manning is "on schedule" in his recovery after breaking his left leg in Houston's 41-7 win over Tennessee in Week 7. Kubiak said a day later than Manning would miss a minimum of four weeks.
"Amazing what he's doing in the training room right now," Kubiak said Friday. "I don't want to put too much pressure on him and say he's ahead (of schedule). I just know he's doing very good."
Fullback James Casey (chest) isn't 100 percent but he will be able to play, according to Kubiak.
Linebacker Connor Barwin (Achilles), linebacker Brian Cushing (knee), linebacker DeMeo Ryans (elbow-wrist-hamstring) and wide receiver Kevin Walter (knee) also will be able to play despite missing some practice time this week.
Information from The Associated Press and ESPN.com senior NFL writer John Clayton was used in this report.