Roberts started at hooker and produced a strong display as Ayr returned to winning ways in the Arnold Clark Premiership, with the Scotland U20 international earning the Player of the Match award.
Elsewhere, fellow Warriors academy player Dylan Cockburn came off the bench as Melrose claimed a 31-26 victory away to Edinburgh Academicals.
Gregor Johnston, who has been training with the Warriors squad, was also in club action, starting at scrum-half for Glasgow Hawks in their Premiership meeting with Kelso.