The secretary-general repeated his call for de-escalation and for all parties to "refrain from hasty actions and provocative rhetoric." Instead, he urged "all parties ... to engage in direct and constructive dialogue."
He appealed to the international community to continue to support "the key actors to calm the situation and work toward a durable and fair political solution."
If the situation in Ukraine deteriorates, the UN head warned, that could lead to further crisis.
"A further deterioration of the situation would have serious repercussions for the people of Ukraine, the region and the global community."
Ukraine, he said, is at a "crucial juncture" that "cannot afford either miscalculations or inaction." The crisis must be resolved peacefully and must respect "the unity, sovereignty and territorial integrity of Ukraine."
The Crimean parliament voted Tuesday to declare independence from Ukraine, a move that was deemed unconstitutional by Ukraine's acting president and Ukraine's national parliament. Also Tuesday, Ukrainian President Oleksandr Turchynov announced the creation of a new national guard that will be mobilized -- along with Ukraine's armed forces.