With a disappointed sell out crowd of 3,255 looking on, Canada could only manage to get points off three penalty goals by Connor Braid, one in the first half and two in the second.
He finished the tournament with eight penalty goals in all.
Argentina, with nine new starters from their previous game against Uruguay, were the much more structured team and led 13-3 at halftime.
Playing with an extra man after Canadian scrumhalf Sean White was handed a yellow card, Argentina's Ramiro Moyano scored a try under the posts with ten minutes to go in the first half.
Halftime score had Argentina leading Canada 13-3.
Braid gave Canada some hope seven minutes into the second half when he brought Canada close (13-6) with his second penalty goal. Iglesias answered back at the 16 minute mark with a penalty goal from 15 yards out.
After Braid's third penalty goal made it 16-9, Argentina's offence countered when Ramiro Moyano intercepted a dropped ball from Canada's captain Tyler Ardron and ran it in.
Matias Orlando sealed the victory for Argentina with a final try in the right corner, with Iglesias missing the conversion.