It seems to be somewhat an ends/means disagreement. Many branches of libertarianism argue that government interference with private contracts is inherently wrong. Other pro-capitalist views (Hayek among them), though, focus more on the outcomes, arguing that capitalism is good because competitive markets with decentralized decision-making mediated by price signals produce the best outcomes for humanity. Those holding the latter view don't have as blanket an opposition to all kinds of regulation, but would allow some kinds of regulation that are narrowly tailored towards promoting competitive markets. Adam Smith is probably the earliest precursor of that view; for example, he opposed most regulation, but supported requiring employers to pay wages in silver, because he thought on balance, prohibiting employers from paying their employees in IOUs promoted a functioning market economy, so the interference with the employer's absolute freedom to negotiate payment methods with their employees was justified. Hayek outlined a number of kinds of intervention he felt justified as well.