"I have seen players do that before, and we all have," Jackson said, per ESPN.com's Pat McManamon. "I have had some of the great ones in this league drop balls.
"But we can't do that to a young quarterback because he needs guys to make as many plays for him as they can in this situation. I think Kenny gets that. He knows that is inexcusable. He has to make that play for the quarterback."
Britt's drop came with Cleveland facing 2nd-and-19 with 11:27 left in the game. It trailed 21-10 and punted two plays later.
While Britt is in the first year of a four-year, $32.5 million contract—a deal that included $17 million guaranteed—Jackson wouldn't commit to keeping the 28-year-old in the lineup.
"Let's see where we go this week," he said. "Let's see what we are doing this week. Let's find out. You are saying that he is starting this week. We don't know that. Let's see where we are this week and go from there."
Sunday's performance will have been familiar to fans of the Tennessee Titans and Los Angeles Rams who watched Britt before he joined the Browns. According to Pro Football Reference, he ranks 78th in catch rate (54.5 percent) among 92 receivers with at least 100 catches since he entered the league in 2009.
Britt is coming off a 2016 season in which he caught 68 passes for 1,002 yards and five touchdowns—production that helped him secure his lucrative contract. Before last year, though, he had never registered more than 48 receptions in a season.
The Browns may be paying Britt to be their No. 1 wideout ahead of Corey Coleman, but Sunday's performance—along with his past numbers—will likely lead some fans to wonder whether he's much of an upgrade over Terrelle Pryor Sr., whom Cleveland didn't re-sign in the offseason.