ISTANBUL 

Iranian presidential adviser Hamid Aboutalebi said Tuesday that the U.S. return to the 2015 nuclear deal is a precondition for talks between Washington and Tehran.

"Respect for the great nation of Iran, reduction in hostilities, U.S. returning to the nuclear deal... That will open the rocky path of the moment," Aboutalebi wrote on Twitter.

On Monday, U.S. President Donald Trump said that he was ready to hold talks with his Iranian counterpart Hassan Rouhani without preconditions.

In May, Trump withdrew the U.S. from the nuclear deal, which was signed in 2015 between Iran and the P5+1 group of nations (the five permanent members of the UN Security Council plus Germany).

The nuclear deal places restrictions on Iran’s nuclear program in exchange for billions of dollars in sanctions relief.

During his electoral campaign in 2016, Trump had criticized the agreement, describing it as the “worst deal” he had ever seen. Other members of the P5+1, however, say the deal in its current form represents the best means of reigning in Iran's nuclear program.

Reporting by Beraa Gokturk:Writing by Mahmoud Barakat