The United Arab Emirates firm set to take control of six US ports is to delay part of the deal after objections from leading US lawmakers.
The six major ports involved include New York
Dubai Ports World had been set to take over ports from New York to New Orleans by buying UK firm P&O.
But some lawmakers, both Democrat and Republican, warn the deal will make the US more vulnerable to terrorism.
The White House has threatened to veto any law seeking to block the agreement, but said it could accept some delays.
DP World's decision to delay the US part of the P&O takeover will be welcomed by the White House, the BBC's James Coomarasamy in Washington says.
Even the threat of a presidential veto has failed to quell the chorus of opposition and at this point a cooling-off period is probably the best George W Bush could have hoped for, he adds.
A White House spokesman had earlier said that although there might be flexibility over timing, the deal should go ahead.
"The safeguards are in place and the president believes it should be allowed to move forward," Scott McClellan said.
"We also recognise that members of Congress want some additional information and we are glad to provide them with that information," he added.
Six of the largest US ports - New York, New Jersey, Philadelphia, Baltimore, New Orleans and Miami - are currently run by British ports and shipping firm P&O, which has agreed a $6.8bn (£3.9bn) takeover by DP World.
'Sense of calm'
After a cabinet meeting on Thursday, President Bush said: "People don't need to worry about security".
"This wouldn't be going forward if we were not certain that our ports would be secure," he added.
The president again stressed the UAE was an important partner in the US-led war on terrorism.
He said briefings with congressmen were "bringing a sense of calm to this issue".
The deal has angered some senior lawmakers.
Bill Frist, leader of the Republican Party in the Senate, said he would introduce a law to block the deal if the government did not delay it so that an investigation could be held.
Critics fear an increased risk of terrorist attacks, pointing out that the UAE was the home of two of the hijackers involved in the 11 September 2001 attacks.
The president of the Arab American Institute, James Zogby, has described some of the language being used against the deal as "shameful and irresponsible".
President Bush has himself suggested that some criticism of the deal is racist in nature.