Simple answer is yes there was.

The complicated answer is that to some extent the apartheid state from the beginning was anti-democratic and not just in the ways you expect in terms of allowing only whites to vote. The National Party came into power on a minority of the popular vote among whites in 1948 in part because of disproportionate weighting of its core supporters' votes, and having won, the NP proceeded to institute a series of laws and changes to the South African constitution that made it nearly impossible for any democratic opposition even within the white community to successfully challenge their rule. This was not an accident, and it was not merely a case of a political party pursuing its own control in a self-interested way, but was also founded on some degree of suspicion about liberal democracy as such.

But even if you can find your way to saying that the National Party in its apartheid heyday was still democratic both in form and in ethos, in the 1980s as a popular uprising gained steam and the military and police came to the fore as the main governing authority on the ground, right-wing members of the National Party increasingly felt that democratic rule of any kind would be insufficient to the task of retaining power over the country. The most explicit example of this was the founding of the Afrikaner Weerstandsbeweging or AWB in 1973 by Eugene TerreBlanche (notably before the Soweto Uprising in 1976) which called back to pre-1945 support among Afrikaners for European fascist parties. The AWB's vision from its founding was in favor of an ethnonationalist state that would not necessarily be democratic even within its citizenship and certainly had no interest in any broader conception of democracy.

In a less organized and ideological vein, many members of the South African security services and police in the 1980s and 1990s showed little to no interest in democracy as such and were perfectly willing to attempt some form of semi-organized sabotage of the transition to majority rule. If you want a measurement of the extent of this sentiment within the white community, the referendum called by FW De Klerk during negotiations on the interim constitution in 1992 returned a 69 percent majority of whites in favor of continued negotiations for a transition to democratic rule, so you could arguably say that 31 percent of white voters (mostly loyal to the Conservative Party or the AWB) were against democratic rule at that time.