UN resolution 661 was an embargo against Iraq (and occupied Kuwait) and banned the purchase of oil (and any other commoditiy). It also banned the supply of any material other than medical, food, or humatarian aid.

From UN resolution 687 (3 APR 1991):
34. Decides to remain seized of the matter and to take
such further steps as may be required for the implementation
of the present resolution and to secure peace and security in the region