"Whenever we get an opportunity, we will be lobbying for the removal of these restrictions against certain individuals or institutions in Zimbabwe, because we think it's not necessarily helping in making sure Zimbabwe moves forward," she told journalists in Cape Town.
Nkoana-Mashabane also spelled out South Africa's priorities and key policy objectives for the new UN session.
These included movement towards achieving Millennium Development Goal (MDGs) targets, particularly the eradication of poverty; the global financial crisis, especially its impact on Africa; and climate change.
Responding to a question on reform of the UN Security Council, Nkoana-Mashabane was critical of this body's composition, telling journalists it had remained the same since 1945 and "just refuses to change".
But South Africa intended to push hard for change: specifically, for Africa to obtain permanent representation on the council.
"Almost 80% of the UN Security Council's agenda is about African issues. So, we believe Africans need to have full representation - and permanent - on the council.
"We are fully aware that it might not happen within the next two years, but we will continue to work for change," she said.
South Africa would also push for change of the so-called Bretton Woods institutions, which include the World Bank and International Monetary Fund.
Responding to a question, she said that when South Africa called for changes to the global economic architecture, this included "opening up of space for developing countries to also become players".
"We are calling for free trade, acceleration of the conclusion of the Doha [Development] Round. We are calling for market access for African goods and services to the developed world.
"We are also calling for gradual, if not total, removal of agricultural subsidies from the developed world that makes it difficult for smaller countries' products to enter the developed markets," she said.