Manning then led a drive that ended with a touchdown pass to Beckham for a 14-10 lead at halftime.
The Bengals used Alex Erickson's 84-yard second-half kickoff return to set up the go-ahead score. Jeremy Hill had a 9-yard TD run and Cincinnati later added Mike Nugent's 38-yard field goal for a 20-14 lead in the third quarter.
"We have opportunities on offense to put more points on the board and we end up having to kick field goals and that ended up probably being the difference in the football game," Lewis said.
"We've got to find a way to flip the switch and get these games turned into wins rather than a tie in London and a one-point loss here tonight," Dalton said.
Late in the second quarter, the Bengals missed an opportunity when they only mustered a field goal after Dre Kirkpatrick's interception gave them the ball at the 7. They were held to a 25-yard field goal by Nugent for a short-lived 10-7 lead.
The defense, which entered ranked 25th in the league, allowed 351 yards, and the Bengals were penalized nine times for 60 yards.
Penalties, an inconsistent offense and an inability to contain Eli Manning and Odell Beckham Jr. combined to doom the Bengals.
The Bengals finished with only 12 first downs and 264 yards.
The defeat also continued the Bengals' struggles against some of the NFL's top teams in 2016. They also have lost to Dallas, Denver,Wholesale China Jerseys Free Shpping, New England and Pittsburgh.

The Bengals faltered in the fourth quarter, though, and lost to the Giants 21-20 to fall to 3-5-1.
Dalton was 16 of 29 for 204 yards with a touchdown pass to A,NFL Jerseys Cheap.J. Green and an interception.
Cincinnati dropped to 11-23 on Monday night, including 4-7 under coach Marvin Lewis. The Bengals haven't won a road game on Monday night since the 1990 season, also the last season the team won a playoff game.
The fourth-quarter struggles overshadowed a strong start to the second half,Discount NFL Jerseys.
With his team trailing 21-20 early in the fourth quarter, Dalton was intercepted by Landon Collins. George Iloka intercepted Manning on the next play, but the Bengals were unable to take advantage as they failed to get a first down. The Bengals were forced to punt on their next two drives as the Giants sacked Dalton twice.
"We're trying to figure out what we need to do to have these outcomes be different, and there's not one explanation for it," Dalton said.
With no team in control of the AFC North, the Bengals fell further behind in their hope to reach the playoffs for the sixth consecutive season. They host the Buffalo Bills on Sunday.
A road game on Monday night against a winning team was an opportunity for the Bengals to reach .500 for the season,Cheap Jerseys Free Shipping.
EAST RUTHERFORD,Cheap Jerseys From China, N.J. (AP) — Andy Dalton and the Cincinnati Bengals missed another chance to get a statement win.
But the defense couldn't hold the lead as the Giants went for it on fourth-and-goal from the 3 and scored on Manning's third TD pass of the game early in the fourth to retake the lead at 21-20.
"We've got to take a good, hard look at what we're doing and correct the things that are hurting us."