Iranian President Hassan Rouhani was repeatedly interrupted by supporters of Ayatollah Ali Khamenei at a unity rally held in Tehran on Wednesday.

According to reports, the hecklers chanted slogans in support of Iran’s conservative Supreme Leader as Rouhani urged “unity and cohesion” in the face of Iran’s “enemies.”

“The enemies want to create discord among ethnic groups and religions. … The first step is to be united,” Rouhani also said in his speech.

The rally was held at the Imam Khomeini Mausoleum. Ayatollah Ruhollah Khomeini was the leader of the 1979 Iranian revolution that deposed the U.S.-backed Shah and replaced his government with the current regime, which calls itself the “Islamic Republic.”

Nuclear hardliners in Iran believe that Rouhani and Foreign Minister Javed Zarif are making too many concessions to the West in negotiations about Iran’s nuclear program. Although Khamenei has not come out in support of the hardliner position, he has often expressed his doubts about the deal, which leads many to believe he is sympathetic to the more conservative side.

In March, Ayatollah Khamenei condemned U.S. sanctions on Iran, saying “Death to America. They are the original source of this pressure.”

In April, Khamenei blasted the terms of the deal as they stood then, saying the United States would have to make even more concessions before Iran should consider agreeing to the deal. Specifically, he demanded an immediate removal of all sanctions and said that Iran should refuse any deal which would permit inspectors to investigate non-nuclear military sites.

U.S. negotiators want to have a phased rollback of sanctions and fear that non-nuclear military sites will be used for Iran’s nuclear program if left without inspections.

In 2013, Rouhani ran against the more conservative Mahmoud Ahmadinejad and won with a little over 50 percent of the vote. Rouhani is typically considered more willing to work with the West, especially on nuclear issues, than Ahmadinejad was. In an op-ed in The Washington Post published a few months after his election, Rouhani wrote that Iranian leaders need to be more willing to “engage in constructive interaction with the world.”

However, little progress has been made in the nuclear talks, and American critics believe that even if a deal is worked out by the June 30 deadline, Congress may not approve it or the next president may replace it.