Mexico so far has confirmed 26 cases of the coronavirus, with no deaths. In the United States, 48 people have died.
Mexican Deputy Health Minister Hugo Lopez-Gatell said contagion from the United States was a threat.
"If it were technically necessary to consider mechanisms of restriction or stronger surveillance we would have to take into account not that Mexico would bring the virus to the United States, rather that the United States could bring it here," he told a news conference."
He did not provide details. A health ministry spokeswoman said she had no further information.
The possibility of infection is of particular concern to residents in Mexican frontier cities such as Tijuana - just opposite San Diego, California - many of whom cross the border daily for work or school. Many of them now fear picking up the virus in the United States.
However, the relatively low level of proven cases of coronavirus in Mexico - a nation of some 130 million people where sanitary conditions vary considerably - has raised questions about the government's relatively hands-off approach to the epidemic.
Mexican officials have said they are keen to avoid maximizing the economic impact of the virus by imposing sweeping restrictions unless the situation worsens considerably.
US President Donald Trump says coronavirus bolsters his argument for blocking northbound border crossings with a US-Mexico wall.
Trump has long called for a wall to block migrants from entering the United States, and wrote on Twitter that the barrier is now needed "more than ever" as coronavirus spreads.
"To this point, and because we have had a very strong border policy, we have had 40 deaths related to CoronaVirus. If we had weak or open borders, that number would be many times higher!" Trump tweeted on Friday.
The US ambassador to Mexico, Christopher Landau, called for cooperation on organized crime and illegal migration in comments to Mexican lawmakers on Thursday, and said coronavirus provided yet another reason to implement more border controls.
"For both countries, it doesn't benefit us to have completely open borders," he said. "We see it now with the virus, and hopefully we can work closely together because in health issues, political parties and borders aren't important."
Unlike other Latin American countries, Mexico has not closed schools or banned entry to people coming from places with high numbers of coronavirus cases.
However, the Tecnologico de Monterrey university suspended classes from next week until further notice, while Mexico's National Autonomous University said it would tighten preventative measures to prevent the spread of the virus.
The Guadalajara International Film Festival, set for next week in one of Mexico's biggest cities, said it would be postponed until further notice.