"It depends on whether or not they sign a very strong agreement," Trump told CNN in a phone interview on Sunday.
"The answer is, highly unlikely it's going to be necessary."
CNN did not specify exactly what it had asked Trump, who also said that if strikes resume, the US has identified potential infrastructure targets, including 38 bridges "that we can knock down in literally one hour."
Trump had hinted at renewing major attacks on Iran after last week's US midterm elections, but there has been no sign of a large-scale US military operation.
Iran has said it would respond by striking US and Israeli targets.
Iranian media suggested that explosions in southern Iran on Saturday were related to Iranian military activities rather than US strikes.
Iran's state television said officials had not confirmed any missile strikes on Iranian territory following blasts heard in several areas, including on Qeshm Island in the strait.
Both the US and Iran have continued strikes on vessels in the Strait of Hormuz, however, restricting exports of energy and other commodities vital to the world economy.
Iran's state television said the evening explosions might be related to Iranian military activity in the waterway, where Iran said two vessels had hit mines and a third had caught fire.
The US said its air force had disabled a vessel in the Gulf of Oman beyond the strait.
Tasnim news agency said two missiles had struck Qeshm Island, with no official information on possible damage.
Neither Iran nor the US has commented on that report.
Washington said on November 2 that it had struck the island in a limited defensive measure against Iranians using surface-to-air missiles against US assets.
Since the US and Israel began attacks on Iran in February, Tehran has sought the upper hand by hitting vessels in the Strait of Hormuz to block Gulf energy exports, while US forces began blockading movements to and from Iranian ports in April.
The US military said on Saturday evening that its air force had fired at the stern of a commercial vessel in the Gulf of Oman, disabling it as it tried to get through the blockade.
Iran's Revolutionary Guards Navy said two oil tankers had caught fire after hitting mines while attempting to pass through an "unauthorised route" in the Strait of Hormuz.
A third tanker had also suffered an explosion and caught fire, the semi-official Fars news agency reported later.
Reuters was not able to confirm any of the reported strikes.
Monitors from the United Kingdom Maritime Trade Operations said a bulk carrier and military forces were involved in an incident in the Gulf of Oman, approximately 18 nautical miles east of the United Arab Emirates' city of Khor Fakkan, with damage unknown.
It was unclear if it was related to the reported US attack.
