The 27-year-old was left off the squad for the tournament's group stage, but was added to his country's roster on Wednesday after the team qualified for the quarter-finals.
The call-up means that Waston will miss Vancouver's Major League Soccer game Saturday in Portland against the Timbers. He could also miss the Whitecaps' home date against the San Jose Earthquakes on July 26.
Vancouver, which sits tied for first in the Western Conference, is already without injured centre back Pa-Modou Kah, meaning that youngsters Tim Parker and Christian Dean could get the call this weekend.
The six-foot-five 215-pound Waston has played 19 games for the Whitecaps this season.
MLS also announced Wednesday that Waston has been fined an undisclosed amount for embellishment in Saturday's home loss to Sporting Kansas City. It's the second time Waston has been fined for diving in the last three weeks.