Mayor Charlie Hales said in a press release, "Our main concern is public health and safety, because the state invested in the cities the responsibility to do that. Beyond that, though, is the issue of fairness."
Uber announced it was launching in Portland in a blog post on Friday.
Hales also threatened to fine Uber in a Facebook post on Friday.
"The city will enforce existing regulations," he said. "That could include fines for the company, as well as fines for drivers."
The City's Bureau of Transportation issued two civil penalties for Uber on Monday for operating without a company permit and operating without a vehicle permit.
Uber's website claims it is "not a transportation provider."
We've reached out to Uber and will update this post if we hear back.