Two Ivorian soldiers were injured and at least two civilians were killed in attacks from rebels in western Ivory Coast.
The U.N. mission in Ivory Coast said it was coordinating with peacekeepers from Liberia on border reinforcements.
Ivory Coast in 2011 was pushed to the brink of civil war following disputed presidential elections. Former Ivorian President Laurent Gbagbo is on trial at the International Criminal Court for war crimes, though both sides are accused of committing atrocities.
Rights group accused Ivorian and Liberian rebels of stoking unrest last year. In June, peacekeepers with the U.N. mission in Ivory Coast were attacked while on patrol near the Liberian border.
Liberia's own civil war ended in 2003. Karin Landgren, U.N. special envoy to Liberia, told the Security Council the country has shown a commitment to peace but stressed there was "hard work that still lies ahead."