The embassy said it had “received credible information warning of an attack targeting popular tourist locations” in eastern Arugam Bay.
The warning comes after social media posts called for a boycott of Israeli-owned businesses in the area.
Protests by local Muslim groups against Israel’s war in Gaza and Lebanon have drawn support from the wider community in the predominantly Buddhist South Asian nation.
There was no immediate reaction from Sri Lankan authorities, but police have stepped up security in the area.
There have been no attacks in Sri Lanka since the 2019 Easter Sunday bombings that killed 279 people, including 45 foreign nationals.
The coordinated attack against three hotels and three churches was blamed on a local jihadi group.
Tourism has been recovering since the island’s economic collapse in 2022, with some 1.48 million tourists visiting so far this year.