The men appeared via videolink at the Old Bailey, where a trial date was set at Manchester Crown Court for 15 June 2027. The trial is expected to last five weeks.
Ahmadyan, of Liverpool, and Salehi, of Salford, are accused of conducting hostile reconnaissance at Heaton Park Synagogue, which was subject to a fatal attack last year, and the Jewish Museum in Cheetham Hill. The pair arrived illegally into the UK on boats.
Prosecutors allege the men were in contact with an Iranian national who directed and co-ordinated the planned attack, with the third party most likely operating within Iran. The charges include obtaining instructions to make a chlorine bomb and acquiring liquids, components and equipment to manufacture or assemble an improvised explosive device. They are also accused of using the internet to identify and research potential targets, acquiring images, plans and maps of potential locations, and conducting reconnaissance.
During last year's attack on Heaton Park Hebrew Synagogue, Jihad Al-Shamie, 35, drove into the gates and began a knife attack while wearing a fake suicide belt, killing Melvin Cravitz, 66, and Adrian Daulby, 53.
Both men deny all charges. The next court hearing is due on 16 April 2027.