Protesters from the This Is Rigged pressure group sprayed the entrance red.
The group said on Twitter: “(The Scottish Government’s) silence on new oil and gas is deafening. They must vocally oppose all new oil and gas, or they are complicit.”
An attached video shows activists covering the front of the public entrance in a red substance, including the sign above the door.
This Is Rigged said four of their activists were involved.
A Police Scotland spokesperson said: “We were made aware of protesters at the Scottish Parliament in Edinburgh shortly after 1.40pm on Tuesday August 1.
“Officers are in attendance.”
In April, two women were arrested after throwing red paint on to an external wall of the Parliament building as First Minister’s Questions was under way inside the chamber.
The paint was quickly cleaned from the side of the building by staff using a water jet.
Authorities at Holyrood recently brought in extra security measures to try and prevent FMQs being disrupted by repeated protests from the public gallery.