When contacted, PKR Youth chief Shamsul Iskandar Md Akin said the windscreen of the bus was hit by red paint near Kampung Rim.
Some of the paint could also been seen on the left side of the bus.
"The bus arrived at around 3.30pm at Kampung Rim for an Aidilfitri programme. Suddenly it was approached by 20 people who tried to block our path," he told Malaysiakini.
Shamsul claimed that the perpetrators were BN members because he spotted an Jasin Umno committee member among the group.
Jasin Umno was also accused of being part of the group which attacked an event where Bersih co-coordinator S Ambiga was supposed to speak last May.
The bus was splashed with red paint and its windscreen smashed with a projectile when it was in Kota Bharu last Saturday. The damaged windscreen was subsequently replaced.
'Scuffle with group'
Shamsul said the group had prevented the bus from using a road at the village, prompting the PKR youth squad to confront them.
“There was a short scuffle between our youth squad with the group but eventually they gave way,” he said.
However, as the bus was leaving, red paint was splashed onto its windscreen, he said.
Shamsul added that a police report would be lodged after they conclude their Aidilfitri event.
Meanwhile, PKR supremo Anwar Ibrahim in a Facebook posting described the incident as an increasingly bold act of thuggery.
“Last week it was in Kelantan, now it’s in Malacca. The actions of these thugs are becoming more bold and crude."