"It could have been heatstroke or the result of the animal not being suitable to be used in this way because of its age or other factors," he said.
"We're going to denounce this because it's the third time something similar has happened in the last two months and we have to get to the bottom of what's happened."
A man who appeared to be the horses owner was seen trying to pull it up while three people sat in the carriage, waiting.
Spanish locals approached them and yelled to get down off the cart.
The horse eventually got back onto its feet but it is not known whether it was forced to keep taking passengers around the city.
Animal rights organisation Peta UK has created a petition that specifically calls out horse-drawn carriages in Mallorca.
"Dozens of exhausted horses are forced to pull carriages laden with tourists through the busy streets," the petition reads.
"Many of the debilitated animals collapse – especially in the summer when temperatures regularly reach 35 degrees.
Others get caught up in noisy traffic, which often leads to accidents – the honk of a car's horn or even just an insect bite can be enough to trigger the horses' instinct to bolt."
The petition automatically sends an email to the mayors of Palma, Alcúdia and Sant Llorenç des Cardassar, urging them to ban the practice.
