Ban is "deeply concerned" by reports that Israel issued the tenders for construction, his spokesman Stephane Dujarric said.
"As the United Nations has reiterated on many occasions, the building of settlements on occupied territory is illegal under international law," he said in a statement.
He reiterated a call from Ban on both parties "to avoid taking unilateral actions on the ground that would further diminish the chances of reaching a negotiated final peace agreement."
Israel unveiled the plans in retaliation for the formation of a Palestinian unity government backed by Hamas and the international community, drawing a furious reaction from the Palestinians, who pledged to seek an anti-settlement resolution at the UN Security Council for the first time in more than three years.