The result handed Ireland their second pool defeat and means they will be competing in the Bowl competition tomorrow on the final day of the 2009 World Cup
The Irish will take on the Arabian Gulf side, the tournament hosts, in the Bowl quarter-finals. Zimbabwe v Georgia, Japan v Uraguay and Hong Kong v Italy are the other Bowl quarter-finals.
Speaking after the Portuguese game, Ireland Sevens coach Jon Skurr said: "I think we just tired out a bit. Our Sevens experience is obviously not great, we haven't got a lot of it.
"We just got caught up a few times, we didn't utilise (possession) and we probably wasted a bit too much ball than we would like to.
"But all credit to the guys. These guys have never played Sevens before and we have given a couple of teams on the (IRB World) circuit great games and we proved these boys can play at this level."
An exciting 24-21 victory over Australia, earlier in the day, was only Ireland's 12th win across five Rugby World Cup Sevens tournaments.
Skurr was very happy to see his squad play to their potential and shock one of the Sevens game's bigger hitters.
"(The win) was fantastic for the guys. The guys were absolutely devastated by the performance yesterday against Samoa. They let themselves down and they know that.
"We picked it up against Australia and played some really good Sevens. They didn't have the ball for the first four or five minutes and we went 17-0 up.
"It's a learning curve for the guys. They are learning quickly but it is a harsh process."