WASHINGTON—Colombian coca cultivation rose again in 2017, reaching a new high, according to an official U.S. assessment released Monday that is likely to fuel fresh consternation against a key Latin American ally.

Coca cultivation increased 11% to 209,000 hectares (516,450 acres) from 188,000 hectares (464,558 acres) in 2016, growing for a fourth consecutive year, the White House Office of National Drug Control Policy said in its latest annual calculations of Colombian cultivation and production.

The...