"We need to wait and see what the outcome of the investigation will be", he added.
Still, major airlines from North America to the Middle East kept flying the 737 MAX, though Canadian Transport Minister Marc Garneau said he would not hesitate to take action once the cause of the crash is known.
US President Donald Trump on Wednesday said the United States would ground Boeing's 737 MAX jets, after Australia and other nations stopped the planes due to safety concerns, following a deadly crash in Ethiopia. "Planes that are in the air ... will be grounded upon landing at the destination".
It was the second time the FAA has halted flights of a Boeing plane in six years.
"It's a awful, bad thing". They expressed mixed emotions after finding out the plane they were just on had been grounded by Transport Canada. "The safety of the American people and all people is our paramount concern".
"What we can say is we don't have the capability to probe it here in Ethiopia", he said.
"We understand that regulatory agencies and customers have made decisions that they believe are most appropriate for their home markets. We very much worked in conjunction with Canada".
That breaks with a decision by China, Indonesia and some airlines in other countries to suspend use of the plane. The FAA and the European Union Aviation Safety Agency oversee the world's largest aircraft manufacturers and take the lead in ensuring the safety of their planes.
The aircraft giant said a Boeing technical team is at the crash site to provide technical assistance to the local authorities.
So who's right? And will Sunday's crash affect confidence in modern air travel?
He did not specifically mention the crashes but said that "I don't know about you, but I don't want Albert Einstein to be my pilot".
While the groundings in China and elsewhere are important, most nations typically wait to act until the USA and Europe issue findings on aviation matters. "It has something that has viscerally caught the attention of Canadians", he said. The U.S. FAA said the black boxes were headed to France later on Wednesday.
Federal reports obtained by CNN revealed that USA pilots complained about the MAX 8 in the past.
The FAA also said Boeing will "update training requirements and flight crew manuals to go with the design change" to an automated protection system called the Maneuvering Characteristics Augmentation System or MCAS.
Boeing, which maintained that its planes were safe to fly, said in a statement that it supported the move to temporarily ground 737 MAX flights.
Air Canada and rival WestJet Airlines operate a total of 37 Boeing 737 MAX jets.
"This safety notice restricts commercial passenger flights from any air operator, both domestic and foreign, of the Boeing 737 Max 8 and 9 aircraft - from arriving, departing, or overflying Canadian airspace".
The grounding was welcomed by air workers in the United States. "Decisions such as the one taken today are hard to make, but ultimately important to ensure continued public confidence in aviation", the union said in a statement.
Before Sunday's crash, the 737 Max planes were heavily used, taking more than 9,000 flights in a single week and reaching nearly every continent.