Vancouver has dropped six straight games, including a blowout loss to the Toronto Maple Leafs on Saturday.
Mancini, 23, has played five Canucks games this season, with his most recent action coming Oct. 26. He has yet to record a point.
In the AHL, the right-shooting blue-liner has one goal and five assists in 20 games.
Pettersson, 21, has skated in 38 Canucks games this season with one goal, five assists and a minus-four rating.
Tolopilo, meanwhile, returns to the club less than 24 hours after starter Thatcher Demko was pulled against the Leafs with a lower-body injury. Demko was placed on injured reserve later Sunday.
The 25-year-old Belarusian Tolopilo has appeared in four NHL games this season, posting a .911 save percentage and 2.74 goals-against average.
Vancouver is back in action Monday with a visit to the Montreal Canadiens.
