The Gunners have seven games to play and are 11 points behind the Foxes ahead of Saturday's clash with the sixth-placed Hammers at Upton Park.
"West Ham is a tough proposal, yes, away from home," said Wenger, whose side opened the season with a 2-0 home loss to Slaven Bilic's Hammers.
"They (have) had a very good campaign. When you look at the quality of the players they have, individually they have a good midfield, good strikers and they are solid at the back.
"I think the emergence of (Dimitri) Payet has given them a lot of creativity and efficiency. They have (Cheikhou) Kouyate, (Mark) Noble, Payet, (Manuel) Lanzini - they have a strong midfield and good strikers with (Diafra) Sakho."
Playmaker Payet has been a revelation for West Ham this season and has returned to the France squad ahead of the European Championships.
Wenger is a long-time admirer of the Hammers' $19 million capture from Marseille, but opted against attempting to sign him due to the similar players already at his disposal.
"He has always had top talent, even when in periods he has been a bit up and down," Wenger said.
"But he has been very consistent (this season).
"Historically we always had a great number of creative players - we had (Mesut) Ozil, (Santi) Cazorla, (Jack) Wilshere, (Aaron) Ramsey - they are all offensive players and I've certainly forgotten a few, so we had the numbers."
Ramsey (thigh) and fellow midfielder Mathieu Flamini (hamstring) could return following injuries against West Ham, while Jack Wilshere (leg) and Tomas Rosicky (thigh) were slated to appear for Arsenal under-21s.
Petr Cech could also return to start in goal in place of David Ospina after being an unused substitute against Watford.
Wenger is likely to keep changes to a minimum after wins over Everton and Watford either side of the international break.
"I'm always reluctant to change what works," he said.
"Team play has improved in the those games and our game is based on mobility, speed and technique. We have found a good balance in our games."