The winger was celebrating an anniversary with his girlfriend, half a dozen team-mates and their partners following Saturday's high-profile draw with Leicester Tigers at Wembley when he was attacked.
Ashton, 25, was hospitalised with bleeding on the left side of his face but did not need stitches and escaped otherwise unhurt from the altercation. It is understood he will train today as normal.
Saracens said in a statement: "To prevent confusion, the club would like to clarify events surrounding an incident which took place in London on Saturday.
"Several Saracens players, together with their wives and girlfriends, were enjoying a quiet evening when an uninvited stranger approached the group.
"A brief altercation occurred, which resulted in a friend of this stranger attacking Chris Ashton with a glass. The Saracens winger suffered two minor cuts on the left side of his face, but neither required stitches."
Ashton brought the incident, which has not been reported to police, to light himself by posting a message on Twitter yesterday describing the row. He wrote: "So, some bloke decided to spoil an evening out for me and my misses [sic]. No stitches needed...back to work tomorrow."
Saracens chief executive Edward Griffiths said he was satisfied that Ashton, who signed from Northampton in the summer, had done nothing wrong.
"Since arriving at the club, Chris has proved himself an outstanding member of the Saracens family, on and off the field," Griffiths said.
"It is a reality that well-known sports people are provoked by strangers and subsequent events are instantly tweeted. People will inevitably see this story and say an England rugby player is in trouble again.
"For clarity, Chris Ashton is not in trouble at all. On the contrary, he was celebrating an anniversary with his girlfriend and showed admirable restraint."
Earlier on Saturday the 2011 champions were held to a 9-9 draw by Leicester, with England fly-half Owen Farrell landing just one of five penalties as both sides maintained their unbeaten starts to the new season. Charlie Hodgson, who replaced Farrell in the second half, kicked two penalties and Toby Flood succeeded with three as the showpiece fixture failed to ignite.