SQL & PL/SQL :: Avoid ORA-38104 - Columns Referenced In The ON Clause Cannot Be Updated

this is my test data :

create table tab_1(c1 number,c2 number,c3 number);
create table tab_2(c1 number,c2 number,c3 number,c4 number,c5 number,c6 number);
insert into tab_1 values(1,1,1);
insert into tab_1 values(2,2,2);
insert into tab_2 values(1,1,1,3,3,3);
insert into tab_2 values(2,2,2,4,4,4);

The final result would be, update columns c1,c2,c3 from table tab_1 whith the values of columns c4,c5,c6 from tab_2 where tab_1(c1,c2,c3) exist in tab_2(c1,c2,c3).

My first aproach was :

merge into tab_1
using (select c1,c2,c3,c4,c5,c6 from tab_2) tab_2
on (tab_1.c1=tab_2.c1 and
tab_1.c2=tab_2.c2 and
tab_1.c3=tab_2.c3
)

[code]....

but gets error : ORA-01779

create table temp_table as
select tab1.c1,
tab1.c2,
tab1.c3,
tab2.c4 new_1,

[code]....