Sakho - who has netted 10 times in 23 Premier League appearances in his first season in English football - was withdrawn after 59 minutes during the 1-1 draw with Stoke City on Saturday.
But, despite speculation that his campaign is over, Sakho could return before 2014-15 finishes.
"After undergoing a scan on Monday, Sakho has been diagnosed with a thigh strain and will now commence rehabilitation with a view to returning to action before the end of the season," Stijn Vandenbroucke, West Ham's head of medical and sports science, told the club's official website.
Vandenbroucke also confirmed that Enner Valencia suffered a foot injury against Stoke that will be monitored.
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