"We’re loading up the ships with the best weapons ever made, even at a higher level than we use to do a complete decimation," Trump told the New York Post.
If no deal is reached, the US will be using them "effectively," he added.
The upcoming talks are expected to focus on key US demands, including the transfer of an estimated 1,000 pounds of deeply buried enriched uranium and ensuring the continued reopening of the Strait of Hormuz to international shipping.
On Tuesday night, Trump said that he had agreed to a two-week bilateral ceasefire with Iran. Negotiations between Washington and Tehran on settling the conflict are expected to take place in Islamabad on Saturday morning.