The Citi Open in Washington, D.C., which was scheduled to restart the men’s tennis tour next month, has been canceled for 2020.

The tournament was set to begin on Aug. 14 and serve as a lead-in event for the United States Open. But Mark Ein, the Citi Open chairman, said concern about international travel restrictions and recent trends in the coronavirus had led to the cancellation.

“When we committed to host the event all the trends were going in our favor, and halfway through the process they all reversed,” Ein said by telephone on Tuesday. “Then we ran out of time. With a little more time we may have been able to overcome the obstacles that were in front of us, but it’s better to make a decision for all the stakeholders before it gets to the last minute.”

The decision, made on Monday, will increase doubts about this year’s U.S. Open, which is scheduled to be played without spectators in New York from Aug. 31 to Sept. 13.

But Stacey Allaster, the U.S. Open tournament director, reaffirmed Monday that plans remained on track for a doubleheader at the U.S.T.A. Billie Jean King National Tennis Center. The Western & Southern Open is to be played there from Aug. 22 to 28 as a prelude to the U.S. Open, with players and officials operating inside a health and safety “bubble” similar to those being used by the N.B.A. and other leagues.

“We are all in,” Allaster said.

On Tuesday, the United States Tennis Association said in a statement that the Citi Open decision in “no way impacts the U.S. Open or the Western & Southern Open” and that the organization would create a “safe and controlled environment” at the U.S. Open that has been approved by the state of New York and meets city and federal standards.

“We constantly base our decisions regarding hosting these tournaments on our three guiding principles that include safety and health of all involved, whether hosting these events are in the best interest in the sport of tennis and whether this decision is financially viable,” the U.S.T.A. added. “We are confident we remain in-line with all three guiding principles.”

The Citi Open also had a “bubble plan” and had hoped to group players in an official hotel with testing and health monitoring. It had preliminary interest from some of the top men’s players in the game, including Daniil Medvedev and Stefanos Tsitsipas.

“The big issue really wasn’t a bubble plan,” Ein said. “The big issue is immigration, getting people back and forth in and out of America. We don’t have clarity around that.”

The Citi Open cancellation, which comes in the week that the W.N.B.A. and Major League Baseball are planning to resume play, underscored the unusual challenges that professional tennis faces as an international sport that shifts venues and continents on a regular basis.

Because of the rise in coronavirus cases in the United States, the European Union is not allowing American travelers to enter. And though the United States is allowing foreign athletes to enter, there are lingering uncertainties about whether athletes would be required to quarantine upon arrival. It also remains unclear whether European players would have to quarantine upon returning to Europe.

Ein said he believed the Citi Open cancellation might help to expedite the clarification process.

“I do think the European events are definitely going to happen, and I think the U.S. Open has a really good chance to happen,” Ein said. “I think our cancellation could accelerate the resolution of those immigration issues. I think that’s going to make it a focus. You can’t figure these things out the week before the event.”

Ein, an entrepreneur who was once a ball boy at the Washington event, said he and his team were “heartbroken” to call off the tournament. He added that the prospect of holding it this year became less attractive when it became clear that spectators would not be allowed on site.

Though exhibitions are being staged regularly on a regional basis and though World TeamTennis is being played at the Greenbrier resort in White Sulphur Springs, W.Va., the regular men’s and women’s tours have been shut down since March.

The WTA Tour plans to be the first to resume with a clay-court event in Palermo, Italy, from Aug. 3 to 9. That will be followed by a clay-court event in Prague and a new hardcourt event, the Top Seed Open, in Lexington, Ky., from Aug. 10 to 16, which has commitments from Serena and Venus Williams.

But the ATP Tour has no plans to fill the gap left by the Citi Open’s cancellation. “I know how hard Mark Ein and his team have worked to adapt to new and continually changing conditions and would like to recognize their outstanding commitment to staging the event,” Andrea Gaudenzi, the ATP chairman, said in a statement. “Unfortunately for the moment there are still large factors at play, which are outside of our control.”

For now, the ATP season will resume in New York with the Western & Southern Open, followed by the U.S. Open.

But those events, if they do take place, are uncertain to attract full-strength fields with some men’s players likely to remain in Europe and restart their seasons on clay. Novak Djokovic, the world’s top-ranked player, and Rafael Nadal, the reigning U.S. Open men’s singles champion, are among those considering that option.