An Interstate Commerce Commission official yesterday warned Greyhound Bus Lines that it could face fines or legal action the next time it abruptly cancels commuter service as it did a week ago on the Annapolis to Washington and laurel to Washington routes.

The ICC began an investigation this week into the cancellation, and said yesterday that Greyhound's action was "highly irresponsible, particularly in light of the fact that your riders were provided no prior notice and consequently had no opportunity to seek alternate transportation to Washington."

ICC's regional managing director, Ivan M. Schaeffer, said in a letter to Greyhound that because the 17 commuter runs were canceled and those buses were used on "more lucative" charter trips, Greyhound engaged in "discrimination in favor of charter operations by the carrier and as such is viewed most seriously by this commission."

Schaeffer said that he received many complaints from riders criticizing the manner in which Greyhound canceled the buses. Schaeffer also said he was "further distressed by the lack of cooperation" from Greyhound during his investigation.

Future abrupt cancellations "may well subject Greyhound to legal action by this commission including potential fines or other legal proceedings..." Schaeffer said.

A spokesman for Greyhound President Frank L. Nageotte said that as of 6:30 last night, company officials had not received Schaeffer's letter and therefore they would not comment.