A man threw two grenades into the grounds of the United States consulate in Turkey's southern city of Adana, damaging a wall but causing no injuries, officials said.
Turkish police arrested the man, in his 30s, after he entered the garden of the consulate and threw the hand grenades towards the main building, shattering windows.
The United States has warned its citizens against possible attacks from Turkish guerrilla groups, particularly the far-left Revolutionary People's Liberation Party-Front (DHKP-C).
Police were investigating whether the man was connected with any outlawed local groups, which also include Kurdish and Islamist militants, the state-run Anatolian news agency said.
DHKP-C has claimed responsibility for several attacks on government and civilian targets in recent years, including the US consulate in Istanbul. It said it was behind an early-June attack on Turkish court officials in Istanbul, which injured five people including a prosecutor.
A small bomb exploded outside the British consulate in Istanbul in early April, badly damaging a door. Police suspected the attack was a protest against the war in neighbouring Iraq, which most Turks oppose.
The United States is relocating its consulate in Istanbul to heavily fortified buildings outside the city centre partly due to concerns over security.