The protesters on Friday presented a memorandum to a Foreign Office spokesman demanding Pakistan drop out of the alliance, which was announced in December, AFP reported.
"Neither the Pakistan army nor the nation is for rent, we will oppose any attempts to sell the army to the house of Saud for a few billion riyals," said activist Gul-e-Zahra, addressing Friday's rally.
Pakistan announced on Thursday they would join the so-called alliance to fight "terrorism" in the Islamic world, following a meeting between Riyadh's Foreign Minister Adel al-Jubeir and Pakistani Prime Minister Nawaz Sharif.
Saudi Arabia announced the coalition last month, naming Pakistan as a member, but Islamabad had initially reacted cautiously saying it needed further details before deciding the extent of its participation.
The decision by the monarchy to form the coalition comes as confirmed reports suggest that the Royal family along with Qatar have been aiding and abetting the Takfiri terrorist groups operating in Iraq and Syria for a long time, providing them with funds and arms via Turkey.