DUBAI, April 20 (Reuters) - Iranian President Masoud Pezeshkian said on Monday that every rational and diplomatic path should be used to reduce tensions with the U.S., but added that vigilance and distrust in interactions with Washington were an "undeniable necessity", according to the state news agency IRNA.

A two-week ceasefire between Iran and the U.S. is set to expire on Wednesday, with U.S. representatives set to reach Islamabad for Iran negotiations on Monday while Tehran has yet to announce whether it will send a delegation to Pakistan.

Iranian state TV quoted an unnamed informed source as saying there were no plans for a second round of negotiations due to the U.S.' "excessive and irrational" demands as well as its changing stances.

The adversaries are at loggerheads over the Strait of Hormuz, where Iran tightened control over maritime transit as the U.S. continues to blockade Iranian ports and on Sunday took custody of a vessel trying to get past the American blockade.

Both Iran and the U.S. have accused each other of violating the ceasefire. Pezeshkian said the U.S. blockade showed that Washington was moving toward "repeating previous patterns and betraying diplomacy", according to state TV.

(Reporting by Dubai Newsroom; Editing by Toby Chopra and Kevin Liffey)