The Senegal international featured in the Hammers' surprise 2-0 win over Arsenal in their Premier League opener at the Emirates Stadium on Sunday.
However, it has now emerged that the 25-year-old was taken in for questioning on suspicion of assault by police after they were called to his home in Essex on Thursday.
"The 25-year-old was arrested on Thursday, 6 August at an address in Emerson Park, Hornchurch.
"He was taken to an east London police station and has been bailed to a date in late September."