Dozens of Extinction Rebellion protesters staged an 11-hour blockade outside an Edinburgh-based finance company which invests in fossil fuels.
They claim Baillie Gifford increased the Scottish Parliament's pension investment in oil firm Shell despite MSPs backing action on climate change.
Campaigners blocked entrances at the Greenside Row office.
A spokesman for Baillie Gifford said the investor took climate change seriously.
He added that its fund strategies were increasingly geared towards "supporting a transition to a low carbon economy".
Green MSP, Andy Wightman, who was at the demonstration, said elected members at Holyrood were legally powerless to prevent investments into fossil fuels, but that it had to stop.
Mr Wightman said: "It's not just the Scottish Parliament's pension fund, it's investors across the world who should be divesting in fossil fuels. Fossil fuels are not the future."
He believed that it was time for "people with money" to take it out of companies "who are investing in dead end damaging industries" and put it into "new emerging green technologies".
Mr Wightman added: "We don't have legal direct control over the pension fund, it's in the hands of pension trustees and in recent weeks they have been beginning to make moves to review the pension fund but it is quite difficult under pension rules when they have legal fiduciary duties."
One campaigner, Lauren Waterman, from Extinction Rebellion, said: "We are here because Bailey Gifford manages the MSPs pension funds and despite MSPs claiming they would try to have more ethical pension funds they have upped their investment in Shell by 19%, so that is hundreds of thousands of pounds that are now going into the fossil fuel industry.
"It is impossible to see now how MSPs could properly regulate the fossil fuel industry when they are profiting from it so that's why we are here and we are here to ask them to divest."
In light of the protest, a Baillie Gifford spokesman said: "We take climate change seriously and are proud of being early investors in some of the world's most progressive and innovative companies.
"Our focus is on long term growth investments for our clients which means our investment strategies are increasingly geared towards supporting a transition to a low carbon economy."