The Spaniard moved to North Africa in late May with seven Betway Premiership fixtures still to play, choosing to step away from the Soweto giants to begin preparations with Al Ahly ahead of the FIFA Club World Cup.
Riveiro says he felt confident of making an impact in Egypt after what he considered encouraging performances in the USA, only to be taken aback by how little patience he was afforded once the league campaign began.
"We unfortunately couldn't start the way we wanted to. I think the people were realising that we were trying to do something different with the group and changing the style of the team in a very short space of time.
"We only had 10-11 training sessions before the Club World Cup started, and there were many new signings joining the group. In terms of performance, I was quite happy and the fan reaction was very positive. Unfortunately, the beginning of the season did not play out the way we had hoped, and it only took four games for people at the club to lose their patience."
The 50-year-old, who is back in SA as the Carling Black Label ambassador, is adamant that with more time he could have made a success of his Ahly spell.
Riveiro says his spell in Cairo was defined by limited backing, not results.
"Its a difficult place, lets leave it there."
"It wasn't only about the results, we wanted to do a lot more when we arrived, but you need the proper support to do it, and we didn't have it."
Nicknamed ‘The Spanish Guitar’ by Pirates fans, Riveiro revealed he was forced to leave early due to the terms of his Ahly contract.
"I don't look back in life. The decision was made in specific circumstances, and it's easy to make decisions with tomorrow's journal. I didn't leave Pirates to move to Al Ahly, it was a decision that was made a long time ago. The only thing that I didn't like was that I needed to move across before the local PSL season ended."