The NATO-led KFOR force said unknown attackers threw two grenades at NATO barracks at the tense border between Kosovo and Serbia.
There were no casualties.
The KFOR mission said in a statement that the incident occurred early in the morning of June 19 at the Brnjak crossing point in northern Kosovo.
It said only one of the grenades exploded, causing one KFOR soldier to suffer slight hearing loss.
KFOR peacekeepers have shut the crossing "until further notice" and called in experts to remove the unexploded grenade.
Tensions in Serb-populated northern Kosovo, which does not recognize the government in Pristina, have flared again since KFOR moved in to remove Serb-erected roadblocks earlier this month.
Based on reporting by AFP and dpa