The Italian midfielder rose well at the far post in first-half injury-time to head the only goal of a competitive encounter at Rugby Park.
Killie, who are yet to concede a goal this season, maintained their edge and finished strongly after Hamilton winger David Graham was sent off.
Both sides were unchanged and competed hard in the middle of the park as the game started at a high tempo.
Kilmarnock began to push the visitors back but they were finding it hard to create chances, although referee Crawford Allan inadvertently set up their first opportunity in the 20th minute.
Tony Stevenson’s clearance cannoned off Allan and went behind, leaving the referee no option but to award a corner.
Mehdi Taouil found Frazer Wright six yards out but the defender’s header under pressure was just too high.
Chris Swailes headed over following a Stevenson free-kick and both sides came close to carving out openings with some slick moves as the game opened up.
Graham continued a fine run after a reverse pass from Simon Mensing but his ball across the goalmouth evaded his team-mates.
A one-two between Conor Sammon and David Fernandez almost put the Irishman through but Swailes intercepted.
The chances continued to improve and Killie winger Danny Invincibile volleyed over after James Fowler’s cross found him 12 yards out.
Graham shot wide from 20 yards as Hamilton attacked in numbers and Alan Combe had to backtrack to push over Stevenson’s deep free-kick.
Tomas Cerny made a point-blank save to deny Simon Ford after Sammon headed on Taouil’s corner but the Czech keeper was beaten seconds later.
Taouil delivered to the back post this time and Pascali rose to head down and into the net.
Hamilton manager Billy Reid brought on striker Joel Thomas for his debut, switching to a 4-4-2 system as holding midfielder Alex Neil went off.
Taouil almost set up Killie’s second when his cross found Craig Bryson eight yards out, but Mark McLaughlin threw himself in the way to divert the midfielder’s header over.
Killie captain Garry Hay took a yellow card for a trip on James McCarthy but the alternative could have been more damaging as the breaking midfielder had Thomas unmarked to his left.
McLaughlin had to limp off in the 50th minute with an injury picked up in his goal-saving challenge, with David Elebert coming on.
Killie protected their lead by keeping Hamilton on the back foot and Bryson again came close midway through the half.
He picked up the ball 10 yards inside the Accies half following impressive hold-up play from Sammon and bore down on goal, but he flicked the ball just past the far post as Cerny came out to narrow the angle.
Accies enjoyed a fine spell of unbroken possession involving most of their team, which ended with Stevenson crossing for Richard Offiong, but Wright diverted his header behind.
Their comeback hopes were shattered in the 78th minute when Graham was handed a straight red card for fouling Pascali from behind after losing possession.
Killie handed on-loan Coventry striker Donovan Simmonds his debut as they sought a second goal.
Taouil flashed a shot wide after good skill on the edge of the box and Cerny blocked Invincibile’s low strike as Killie made their extra man count.
The Australian then headed wide at the far post and Taouil again shot wide after some eye-catching skill on the right.