The Saracens winger, 28, has been given a 10-week ban, ruling him out of the Six Nations days after being recalled by England after an 18-month absence.
Ashton was cited for making contact with the eyes of another player and Saracens are considering an appeal.
Winger Rokoduguni, 28, will join up with the squad until a final decision is made on Ashton's case.
Fiji-born British Army solider Rokokoduguni signed a two-year contract extension at The Rec last week. He won his first and only England cap in November 2014 against New Zealand.
England begin their Six Nations campaign in Scotland on 6 February, ending it on 19 March in France.
Saracens and Ashton had three working days to decide on whether to lodge an appeal after receiving the written judgement on Friday.
Bath wing Semesa Rokoduguni has been called up as cover for the banned Chris Ashton by new England boss Eddie Jones.