Yes, JEE Main is compulsory to get admission in Nirma University.

Nirma university takes admission in three ways

1- 50% seat of the total intake will be filled in by the Admission Committee for Professional Courses (ACPC, GoG). These seats shall be filled-in by the candidates who have passed the qualifying examination from the schools located in the State of Gujarat including Diu, Daman and Dadra Nagar Haveli. These seats shall be filled as per the guidelines of ACPC. Candidate has to apply to ACPC, GoG, separately

2- 35% (All India) seat of the total seats will be filled-in by Institute of Technology, Nirma University. These seats shall be filled from the candidates who have passed the qualifying examination from the schools located in India (including Gujarat State) and have appeared for JEE (Main) examination.

3- 15% NRI seats will be filled-in by Institute of Technology, Nirma University.

• NRI seats will be filled in by the Candidate who have passed the qualifying examination abroad and is exempted from appearing in JEE (Main)-2017 or candidate who have passed qualifying examination from the school located in India and having NRI status
• NRI sponsored seats will be filled by the candidates who have passed the Qualifying Examination from the schools located in India (including Gujarat State). Merit list for these seats shall be based on the All India Rank of JEE (Main)
  
  -Candidate should have appeared JEE (Main) (For 35% All India Seats and NRI Sponsored Category).
  -Candidate must have passed 12th Science Examination with Physics, Chemistry and Mathematics with the percentage of marks as to be decided by the Government of Gujarat under the rules of admission.

Good Luck!!

Nirma University provides admission through 3 channels like ACPC Vacant Seats (50% Seats) Category, All India (Jee) (35% Seats) Category and NRI/NRI Sponsored (15% Seats) Category. So you can apply for the same as per the eligibility provided by them which is mentioned below -

Nirma University eligibility criteria
Hope this helps!!!

Nirma University takes the admission through JEE Main & GUJCET for B.tech. For further detail about the seats & admission you can go through with given below link.

Nirma University Admission

Eligibility

Candidate must have passed 12th Science Examination with Physics, Chemistry and Mathematics with thepercentage of marks as to be decided by the Government of Gujarat under the rules of admission and appeared inJEE (Main) 2017 and/or GUJCET-2017 for admission to B. Tech. Programmes. For further you can go through with given below link.

Nirma University